Eurosceptics are spreading absurd stories about Europe's draft new constitution in an effort to "spook" the British public, says Tony Blair.
In a speech in Poland, the prime minister said anti-Europeanism was an "out-of-date delusion" and did not equate to British patriotism.
No referendum was needed on the draft constitution because the UK was winning the argument against the idea of European superstate, he insisted.
Mr Blair has now arrived in Russia for St Petersburg's 300th anniversary celebrations.
Several of the 40 leaders attending the event will, like Mr Blair, travel on to the G8 summit in Evian, France.
During his Polish visit, Mr Blair was visibly irritated as he rejected as "completely absurd" claims that intelligence reports about Iraqi weapons were "sexed up" by the government.
There is mounting pressure from the Conservatives and others for British voters to have a say on the outcome of the Convention on the Future of Europe.
Mr Blair said critics of the convention were trotting out propaganda because they wanted British withdrawal from Europe - something which would be a "disaster".
He pointed to the "frights and terrors about Europe designed to spook us.
"The end of a thousand years of British history.
Absurd stories that we'll lose
the proceeds of North Sea oil, we'll lose our seat on the United Nations
Security Council, we'll lose two million jobs, we'll be forced to drive on the
'Union of nations'
He continued: "My passionate belief in Europe is not born of
any diminishing of my belief in Britain... anti-Europeanism is not British
patriotism, it is an out-of-date delusion.
"We want a union of nations, not a federal superstate, and that vision is
shared by the majority of countries and people in Europe."
Mr Blair said enlarging the EU without changing the way it worked would produce "paralysis rather than progress".
"If the convention represented a fundamental change to the British
constitution and to our system of parliamentary democracy, there would be a case
for a referendum. But it doesn't.
Michael Ancram says Blair is dodging honest debate on Europe
"The truth is the argument, advanced by both our countries, against a
European superstate is being won."
Conservative shadow foreign secretary Michael Ancram argued giving Europe a constitution for the first time was exactly the kind of fundamental change that needed a referendum.
Mr Ancram said: "Tony Blair refuses to hold an honest debate on the European constitution.
"All he will do is offer the British people a false choice between surrendering national sovereignty or pulling out of the EU."
'Partner not servant'
Liberal Democrat foreign affairs spokesman Menzies Campbell argued the prime minister could help defuse the "artificial hysteria" over the draft constitution by saying there could be a referendum if there were constitutional implications for the UK.
Poland supported the US-led war against Saddam Hussein's regime and, like the UK, is due to send troops there on peacekeeping duties.
In his speech, Mr Blair stressed the importance of nurturing that relationship with the US, following the splits over the Iraq conflict.
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It reads like something a bunch of mediocre, lawyer bureaucrats put together
"Where in Europe there is disagreement with the United States, we should manage the disagreement carefully as between allies, not let it explode into a diplomatic dogfight," he said.
In turn, the US could recognise Europe's dilemma of wanting to be "America's partner, not its servant".
On Friday, all 105 members of the convention are debating the draft new constitution, which was published earlier this week.
The UK Government representative there, cabinet minister Peter Hain, warned that the proposals on foreign and defence policy could undermine Nato.
Mr Blair used his visit to Poland to urge voters there to support joining the EU in the country's 7 June referendum.
Flanked by Polish premier Leszek Miller at a news conference, Mr Blair said a "yes" vote was of vital importance to Poland and to the whole of Europe.