Labour’s triple election winner fears referendum would cause instability not seen in Britain since second world war – and praises Ed Miliband’s convictions.
Mr Blair said Mr Cameron had put “exit on the agenda” by pledging a vote and that leaving would threaten the UK’s position as a “great global nation”.
Mr Blair, who was in his old Sedgefield constituency, also gave current Labour leader Ed Miliband his “100%” support.
Mr Cameron has pledged to renegotiate a “better deal” for the UK in Europe and to stage a referendum on the UK’s membership in 2017.
But speaking in his former constituency of Sedgefield in County Durham, Mr Blair said a referendum would be a “huge distraction” and the prospect of possible exit would leave a “pall of unpredictability hanging over the British economy”.
“And the oddest thing of all about having this referendum? The PM doesn’t really believe we should leave Europe; not even the Europe as it is today,” he said.
“This was a concession to party, a manoeuvre to access some of the UKIP vote, a sop to the rampant anti-Europe feeling of parts of the media.
“This issue, touching as it does the country’s future, is too important to be traded like this.”
Mr Blair said leaving the EU would leave Britain “diminished in the world” and take the country “out of the leadership game” globally.