The former Labour Prime Minister told a press conference in London that one of the key challenges in stopping Brexit “Is the absence of an opposition which looks capable on the polls of beating the Government."
"The debilitation of the Labour Party," he added, "Is the facilitator of Brexit. I hate to say that, but it is true."
Mr Blair added that in the absence of an effective opposition, pro-Europeans needed to build a cross-party "movement ".
His comments come four days after one poll showed that for the first time in its history, Labour has dropped to become only the third most popular party among working class voters.
Research undertaken by YouGov found blue collar voters were now more likely to vote for the Conservatives or Ukip than for Labour.
Calling for people of all parties to oppose Brexit, given the current weakness of the Labour Party, Mr Blair said: "What this means is that we have to build a movement which stretches across party lines; and devise new ways of communication.
"These groups must find ways of concerting strategy and tactics effectively. We should begin to create informal links immediately and then build them into a movement with weight and reach.
"We need to strengthen the hand of the MPs who are with us and let those against know they have serious opposition to Brexit at any cost."
He said that the institute which he was launching would play its part in developing the arguments to rethink the country's position - a task that would involve changing people's attitudes towards the kind of globalisation that many now blame for low wages and job insecurity.
Speaking at the headquarters of the Bloomberg financial news agency in London where David Cameron first set out his plan for an EU referendum, Mr Blair said: “The Institute which I am setting up will play our part. We are creating a policy platform wider than the Europe question.
“There is an urgent need to reposition the whole debate around globalisation and how we make it work for people. In this sense, the Brexit debate is part of something much bigger.
“But developing the arguments around Brexit will be an important element of the Institute’s work.”
The ex-PM’s speech, organised by the Open Britain campaign group, came after he announced the creation in December of the Tony Blair Institute. Mr Blair’s office said the new policy unit would be dedicated to developing a “new policy agenda for the centre ground … With the focus of trying to make globalisation work for all” and addressing the “political earthquakes” of the Brexit vote and the election of Donald Trump.
At the time of the creation of his institute, Mr Blair also stressed: “This is not about my returning to the front line of politics. I have made it abundantly clear that this is not possible.”
This, however, is not the first time that Mr Blair, who led Labour to three general election victories, has criticised Mr Corbyn.
In July 2015, as Mr Corbyn headed to victory in the Labour leadership election, Mr Blair intervened to offer the advice: “When people say, ‘my heart says I should be with that politics’ well, get a transplant”
In December 2015, in an article entitled ‘In Defence of Blairism’, for the right-wing Spectator magazine, Mr Blair wrote: “All wings of the Labour Party which support the notion of the Labour Party as a Party aspiring to govern, rather than as a fringe protest movement agree on the tragedy of the Labour Party’s current position.”
Initial reactions to Mr Blair's latest criticism of Mr Corbyn and Brexit appeared mixed.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies