Tony Blair vowed to make it his 'mission' to keep us in the EU today - despite admitting there is 'no appetite' to reverse the historic Brexit vote.
The former PM demanded the public stop worrying so much about immigration and 'rethink' their decision as he delivered a call to arms for pro-Europeans.
In a major return to frontline politics that was condemned as the 'height of arrogance' by Brexiteers, Mr Blair warned that the country was going over a 'cliff edge'.
He also launched a bitter attack on Jeremy Corbyn's role in the referendum campaign, accusing him of 'facilitating' Brexit by being so unpopular.
Former PM Tony Blair demanded the public 'rethink' their decision as he delivered a call to arms for pro-Europeans today
Speaking at an event organised by the pro-EU Open Britain think tank, Mr Blair insisted the public should change their mind about leaving the EU once the consequences are made clear.
In an hour-long address that was condemned by critics as an attempt to 'resurrect his political corpse', Mr Blair:
- Called on Remain supporters to keep fighting against Brexit and raised the prospect that the referendum result could be overturned in a second referendum or general election.
- Lashed out at the way the referendum was conducted with 'hideous abuse' of patriotism, and accused Theresa May or pursuing 'Brexit at any cost'.
- Argued that immigration fears were overblown and leaving the EU would only cut numbers by 12 per cent.
- Conceded that he did not 'spend a lot of time on the doorstep' and did not have 'special knowledge' of the public's views.
- Blamed the 'debilitation' of the Labour Party under veteran left-winger Jeremy Corbyn for letting the Brexit vote happen.
Launching his bid to create a 'movement' against Brexit said: 'I accept right now there is no widespread appetite to re-think.
'But the people voted without knowledge of the true terms of Brexit. As these terms become clear, it is their right to change their mind.
'Our mission is to persuade them to do so.'
Mr Blair hinted that the decision to leave could be overturned through a second referendum or a snap general election.
He accused ministers of leading us into 'Brexit at any cost', saying Mrs May was damaging the economy by ruling out continued membership of the single market.
Mr Blair also complained that the Brexiteers were 'hideously abusing' the 'mantle of patriotism' and diminishing our national interest.
The ex-PM - who oversaw the dropping of immigration controls for eastern European states - said people were wrong to worry so much about numbers coming in from the EU.
'Net immigration into the UK was roughly 335,000 in the year to June 2016,' he said.
'But just over half was from outside the EU.
'I know, in some parts of the country, there is a real concern about numbers from Europe and the pressures placed on services and wages.
In his speech in central London today, Mr Blair conceded there was 'no widespread appetite to rethink' the outcome from June 23 last year
'However of the EU immigrants, the PM has recently admitted we would want to keep the majority, including those with a confirmed job offer and students. This leaves around 80,000 who come looking for work without a job.
'Of these 80,000, a third comes to London, mostly ending up working in the food processing and hospitality sectors. It is highly unlikely that they're 'taking' the jobs of British born people in other parts of the country.'
Mr Blair predicted that Brexit was only likely to cut immigration by around 12 per cent and what actually concerned the public was non-EU migration, which raised issues of 'assimilation and potential security threats'.
WHO IS BEHIND THE OPEN BRITAIN THINK-TANK?
Open Britain is a cross-party group formed out of the defeated Remain campaign that is pushing for the closest possible deal with the EU after Brexit.
Senior politicians from past and present - including Tony Blair, Nick Clegg and Tory Remainers such as Anna Soubry and Nicky Morgan - have made a series of interventions in the name of Open Britain since the June 23 referendum.
They campaigned for Britain to stay in Europe's single market and want a second referendum, claiming the Brexit vote did not give Theresa May a mandate to take us out.
The group wants to retain freedom of movement, arguing that closing our borders would hurt the economy.
The masterminds of Open Britain are the two arch-Europhiles Lord Mandelson ad the millionaire City public relations man Roland Rudd, the brother of the Home Secretary Amber Rudd.
Both men previously tried to drag Britain into the euro and were prominent figures in the failed Remain referendum campaign.
Leave campaigners accused the ex-Labour leader of trying to 'resurrect his political corpse' by deceiving the British people.
Tory MP Dominic Raab said the public just wanted the government to 'get on with making a success of its new place outside the EU'.
'Tony Blair, who allowed uncontrolled migration from the EU when Labour was in power, refuses to accept the decision people made last June,' he said.
'He wants to go on putting the question over and over again until he gets a different answer.
'It is the height of arrogance and nothing could be more likely to convince the EU to offer the UK the worst possible deal than his suggestion that the decision could be overturned.'
Former Cabinet minister Michael Gove said: 'People want politicians to get on with the job of making a success of leaving the EU rather than fighting old political battles.
'Tony Blair had his say during the referendum - he should now respect the fact that the British people voted to leave.'
It follows an intervention last October, when Mr Blair said Brexit could be halted if the people decided the costs of leaving the EU greatly outweighed any benefits.
At the time, he said Britain should keep its 'options open' and not rule out a second referendum.
Describing the June 23 vote as a 'catastrophe', he said the views of the 16million who backed Remain should not be ignored.
'If it becomes clear this is either a deal that doesn't make it worth our while leaving, or alternatively a deal that's going to be so serious in its implications, people may decide they don't want to go,' he said.
'There's got to be some way, either through Parliament, or an election, or possibly through another referendum, in which people express their view.'
Meanwhile, Mrs May has warned that hundreds of thousands of jobs in the EU depend on ties to Britain.
As she prepares to meet her French counterpart in Downing Street today, the PM also pledged that the UK will not seek to 'cherry-pick' which parts of membership it wants to keep after Brexit.
In an article for French newspaper Le Figaro, she said: 'As we leave the EU, we will seek the greatest possible access to the European single market through a new, comprehensive, bold, ambitious free trade agreement.
Tony Blair and his wife Cherie
'This cannot, however, mean retaining membership of the single market. (French) President (Francois) Hollande and other European leaders have been very clear that this would mean accepting the 'four freedoms' of goods, capital, services and people and I respect their position.
'Britain understands that EU leaders want to continue with the process of integration.
'We do not, to borrow the phrase, seek to cherry-pick which bits of membership we desire.'
Mrs May also highlighted French interest in a good Brexit deal, pointing out that the UK is France's fifth-largest export market with bilateral trade worth more than 50 billion euros last year.
'UK companies are responsible for an estimated 230,000 jobs in France, and French companies for about 370,000 jobs in the UK,' she added.
Mrs May also stressed the UK will remain an 'open and tolerant' country and that French people will 'always be welcome in Britain'.
She reiterated her aim of guaranteeing the rights of EU nationals already in the UK, including more than 300,000 French people, and said she hopes France will do the same for Britons living there.
'I will make securing this reciprocal agreement a priority as soon as the negotiations begin, because this is in everyone's interests,' she said.
Mr Blair suggested Parliament and the public should have the last word on the final deal Theresa May (pictured) strikes with Brussels