In an intervention that triggered outrage from Brexit supporters, the former Labour prime minister said a fresh referendum or general election should be held before the departure from the bloc could be confirmed.
He claimed in an interview on the BBC Radio 4 Today programme: “It is not undemocratic to say we should be entitled to think again.”
Mr Blair‘s remarks were the latest in a series of outbursts since the 2016 referendum vote to quit the EU demanding a re-run of the decision.
They drew a stinging riposte from former chancellor Lord Lamont.
The Tory peer said: “I can think of very few interviews I have heard in my life that are absolutely designed to increase cynicism about politics.
“This was simply an attempt to sabotage the result of the referendum.
“It was straight out of the EU school of referendums – only vote when you know what the result is going to be, if it is a no have another one, if it’s a yes carry on.”
Richard Tice, co-chairman of the Brexit-backing pressure group Leave Means Leave said Mr Blair “and his elite gang” were “still determined to stop Brexit”.
Remainers like the former prime minister were threatening to lead the UK “to the very bad deal which we had in the single market and the customs union”, Mr Tice said.
During robust exchanges with Today programme interviewer John Humphrys, Mr Blair rejected claims that his attempt to scupper Brexit could lead to “civil disobedience”.
The former prime minister claimed he “accepted entirely” the electorate’s verdict to leave but went on to insist: “Democracy doesn’t just stop on one day.”
He said: “I’m simply saying one very, very simple thing, which is that in 2016 you knew you wanted to get out of the European Union but you didn’t see the terms of the alternative relationship.
“If when you see those terms you think it is better to stick with Europe you are entitled to have that say.”
Mr Blair said whether voters were given another say about leaving the EU through an election or referendum was a “second order problem”.
He said: ”You could have an election on the issue.
“You can have a debate about how much but there is little doubt that Brexit is causing economic difficulty.”
insisted health service staff were leaving as a result of Brexit and the Government was not able to focus on the problems in the NHS because its focus was on preparing for exit from the bloc.
“Brexit has a massive distractive impact on dealing with the actual challenges of the country and you can see this so clearly with the National Health Service,” the former Prime Minister said.
Mr Blair dismissed claims he was pushing the case for the elite, telling the programme: “There are elites on both sides of the argument.”
He also criticised Labour leader Jeremy Corbyn for failing to oppose Theresa May’s drive towards Brexit.
The party’s stance meant Labour was unable to make an impact in attacking Government policy.
“First, because the Labour Party is saying that we too would do Brexit, we cannot attack its vast distractive impact.
“Labour could mount such a powerful assault on the Government’s record from the appalling state of the NHS to crime, which through neglect and failure to support the police is on the rise again, if we were saying to the country: here’s the agenda which could be delivered for the people were it not for the fact that all the energies of Government and substantial amounts of cash are devoted to Brexit.
“And, second, it puts us in a vulnerable position when the Government concludes ‘the deal’ some time in 2018,” Mr Blair said.
He added: “I am not disputing that we have had the referendum and I am not disputing the result.
“I am simply saying that the debate doesn’t stop at that point, that you are entitled to say as you see counter-claim and claim is replaced by fact and you see the actual terms of the new relationship, it is not undemocratic to say we are entitled to think again.
“Whether it is a second referendum or an election, that is a second order problem, but it would be a fresh referendum which this time – as opposed to 2016 – would be a choice between two alternatives.”
January 4th, 2018: Express