Tony Blair has said that setting up a separate English parliament would be "unworkable" and "unnecessary".
The population of England accounted for the "vast majority" of people in the UK and did not need more representation, he told his monthly news conference.
Keeping the Union with Scotland was "crucial" to national security and the economy, Mr Blair added.
But the Scottish National Party reiterated its call for a referendum on Scottish independence.
A BBC Newsnight poll suggests 61% of people in England, 51% in Scotland and 48% in Wales support an English parliament.
It also suggests that 73% of people in England and 56% of those in Scotland want the Union to remain.
Mr Blair said: "There is a UK Parliament. There should be one class of UK MP.
"It's a completely unworkable situation to have two different classes of MP."
The current constitutional settlement, including Scottish devolution, was the "right type of partnership for the future", Mr Blair said.
He said a break-up of the Union would have "catastrophic consequences for the Scottish economy" and be an "incredibly regressive and reactionary step".
Mr Blair said: "In commerce, in trade, in security and above all in shared values, the Union of England and Scotland continues to be good for England, good for Scotland and right for the future of Britain so we should celebrate today with pride."
But Steve Uncles of the English Democrats, a group campaigning for an English parliament, told the BBC: "When something has this much momentum, there's only one way things can go.
"The current situation is unfair and English people, who have a sense of fair play, want a change."
He added: "It's rather pathetic that the government hasn't really got an answer as to why it thinks an English parliament is unworkable.
"Until a solution is reached, this issue will be a running sore."
Shadow Constitutional Affairs Secretary Oliver Heald said: "We welcome the results of the Newsnight poll showing strong support for continuation of the Union throughout Great Britain.
"But this does highlight the need for a constructive unionist response... so giving English MPs a greater say over purely English matters."
The Scottish Parliament election in May is expected to focus on the issue of independence.
SNP leader Alex Salmond said: "There's far more support for independence than there's ever been."
He added: "People feel far more Scottish than British."
Transport Secretary Douglas Alexander, who is running Labour's campaign for the Scottish Parliament election, said: "The great outcome of devolution is it allows people to demonstrate their identity within the United Kingdom and, at the same time, not break up the United Kingdom."
Scottish identity was not "one-dimensional", he added, while there were "serious questions" to be asked about the affordability of independence.
"This would respect the devolution settlements in Scotland and Wales and tackle the remaining imbalances in the Union, without going down the road of an English Parliament."
For the Newsnight poll, carried out by Opinion Research Business, interviewers spoke to 883 adults in England, 543 in Scotland and 527 in Wales.
Jeremy Paxman and Kirsty Wark will host a BBC Newsnight debate on independence on BBC Two at 2230GMT on Tuesday.