A British government minister said yesterday the US would be foolish to attack Iraq and hinted she would resign if the Prime Minister, Mr Blair, backed a military strike.
Separately, the Home Secretary, Mr David Blunkett, was reported in a Sunday newspaper to have warned Mr Blair of civil unrest if Iraq was attacked over its refusal to allow access to UN weapons inspectors.
The International Development Secretary, Ms Clare Short, said "crude military action" would not solve the problem of Iraq's alleged programme to rebuild an arsenal of weapons of mass destruction.
"To open up a military flank on Iraq would be very unwise," Ms Short told BBC's On the Record programme in the clearest expression yet of concern from within the Blair government about possible conflict with Baghdad.
Mr Blair, who will fly to the US next month for talks on Iraq with President Bush, has warned that the world must act against President Saddam Hussein to prevent him acquiring and using weapons of mass destruction.
But he faces a wave of dissent within the Labour Party against joining Mr Bush in any military action. About a quarter of Labour MPs have signed a Commons petition expressing "deep unease" at the prospect of British involvement.
The Observer, which says Washington wants up to 25,000 British troops to form part of any Iraqi invasion force, said yesterday that senior military officials had also warned about being sucked into "a perilous open-ended commitment". British officials say they have not received a formal request for troops.
"We mustn't ignore the fact that Saddam Hussein is determined to develop weapons of mass destruction," Ms Short said. "But simply blind military action against Iraq does not address the problem."
Ms Short, who resigned from Labour's shadow cabinet 11 years ago over the 1991 Gulf War with Iraq, said she had not changed her ways.
"I've got lots of bottom lines," she said. "I don't expect the government to breach them. But if they did, I would resign."
Cabinet discussions about Iraq 10 days ago led to media reports of a split at the top of Mr Blair's government.
The Sunday Telegraph quoted Mr Blunkett as warning Mr Blair that Arab and Muslim anger about the Israeli-Palestinian conflict would spill over into serious civil disorder if Iraq was attacked.
"We cannot separate Iraq from the Middle East or we will have major disturbances both internationally and in Britain," Mr Blunkett was quoted by the newspaper as telling colleagues.
Speculation has mounted that Washington might launch military action against Baghdad after Mr Bush described Iraq, Iran and North Korea as forming an "axis of evil" developing weapons of mass destruction.
The US Vice-President, Mr Dick Cheney, is touring Arab countries to seek support for military action if Mr Saddam fails to admit UN inspectors.
Mr Cheney has found little or no support for extending the global fight against terror to Iraq, but he insisted yesterday that US forces were staying put in the Gulf Arab states.
"We have not made any plans to make any change in our military positions with respect to Saudi Arabia," Mr Cheney said in Manama before flying on to Doha.
Saudi Arabia has dissociated itself from any US plan to overthrow the Baghdad regime, reportedly telling Mr Cheney on Saturday there is no question of using an air base in the kingdom to attack Iraq.
Meanwhile, Iraqi envoys are touring the Arab world for support against Mr Cheney. The Deputy Prime Minister, Mr Tariq Aziz, opened a diplomatic offensive yesterday to rally north African states at the same time as Iraq's Vice-president, Mr Ezzat Ibrahim, visited the Gulf monarchies after talks in Jordan, Syria, Lebanon and Egypt.