By Sean Curran BBC News parliamentary correspondent

Deputy Prime Minister John Prescott has confirmed there are differences of opinion in the Cabinet over possible military action in Iraq - but says talk of a split is "prattle".

Almost as soon as MPs left Westminster for the summer recess, opponents of a war with Iraq began demanding that Parliament be recalled to debate the prospect of British involvement.

Many Labour MPs - and not just the usual suspects - have made it clear they are against any military action.

More than 150 MPs have signed a Commons motion tabled by the Labour backbencher, Alice Mahon, condemning any attack that did not have the backing of the United Nations.

Under Britain's rather complicated constitution, only the Crown - acting on the advice of the prime minister and the Cabinet - can declare war

Given the level of parliamentary unease, not to mention the lack of public support for a war, it is hardly surprising that some members of the Cabinet are reported to be unhappy at the prospect of British involvement in a US-led campaign against Saddam Hussein.

The views of these senior ministers are important.

Under Britain's rather complicated constitution, only the Crown - acting on the advice of the prime minister and the Cabinet - can declare war.

No-one is yet talking seriously about Cabinet resignations, but the International Development Secretary, Clare Short, has expressed concern in the past.

The Chancellor, Gordon Brown, is reported to have voiced reservations about the possible cost of any military action.

Party conference revolt

A spokesman for the Leader of the Commons, Robin Cook, has refused to comment on newspaper reports that the former foreign secretary is planning to raise his concerns about the diplomatic repercussions of any attack when the Cabinet next discusses Iraq.

Answering questions from MPs last month in the House of Commons, Mr Cook stressed that "no decision has been taken by the British government on this matter. No decision may ever be taken."

Anti-war campaigners would like to see Robin Cook lead some sort of Cabinet revolt over Iraq.

That seems like wishful thinking as Mr Cook is said to regard Saddam Hussein as a serious threat.

When Labour meets at Blackpool for its annual conference the leadership will be prepared for a revolt over Iraq.

But a largescale rebellion in the Commons would be much more serious.

Clare Short: Expressed concern about war

Senior Labour member Gerald Kaufman - who was shadow foreign secretary when Neil Kinnock was leader - says he would vote with the government but he has warned Tony Blair that there is "substantial resistance" within the Labour Party.

In an article in The Spectator magazine, Mr Kaufman writes that "Tony Blair would find it difficult to support and participate in a war against Iraq, whose majority in the House of Commons was provided by the Conservatives".

The government has always insisted that MPs will be given an opportunity to voice their opinions, but no government in modern times has allowed MPs to vote on military action.

That was a tradition upheld by Deputy Prime Minister John Prescott earlier this week when he refused to confirm that there would be a Parliamentary vote on Iraq.