The BBC's Rageh Omaar reports from Baghdad: Iraq has accepted the Secretary General's appeal to back down

Iraqi Deputy Prime Minister Tariq Aziz told UN Secretary-General Kofi Annan in a letter that the Iraqi leadership had decided to resume co-operation and enable UN weapons inspectors "to carry out their normal missions".

In the letter, Mr Aziz said the reason for the decision was "to give an additional chance to achieve justice by lifting the embargo".

Forces still on alert - Blair

Tony Blair: "Compliance must be immediate and unconditional"

But UK Prime Minister Tony Blair objected to nine conditions he said the Iraqis had attached to the letter, and warned that the standoff was "by no means over yet".

"Any conditions of this nature are unacceptable. Compliance with the agreement must be absolute."

US build-up in the Gulf continues

Forces remained on alert for action "at any time without further warning," he said.

The prime minister said there could be "no negotiation, no further deals, no more amendments".

Clinton cancels trip

Mr Blair was speaking after a series of telephone conversations with President Clinton, who has now cancelled a foreign visit to concentrate on developments concerning Iraq.

A White House spokesman said Vice-President Al Gore would represent Mr Clinton at the Asia Pacific Forum meeting taking place in Malaysia.

The president still hopes to complete the latter stages of his planned Asian tour by visiting Japan, South Korea and Guam.

Annan: 'Requirements met'

Earlier Mr Annan said in New York that in his opinion the Iraqi response met UN requirements.

He is due to present the letter to the UN Security Council, which is meeting to discuss the weapons crisis later in the day.

Kofi Annan: The letter appears to have provided the solution

But UN Correspondent Rob Watson says the final decision will rest with the United States, which has been assembling a large military force in the Gulf.

A naval battle group fronted by the aircraft carrier Enterprise has been ordered to speed up its arrival in the Gulf and 129 more fighter planes - including 18 B-1 and B-52 bombers and 12 F-117A radar-evading stealth planes - have been sent to the region.

President Clinton's national security advisers are meeting to assess the Iraqi move.

UN Special Envoy Pakash Shah's statement

The president has declined to give any initial reaction, although the US defence department says its military build-up in the Gulf will continue.

According to Washington Correspondent Stephen Sackur, Baghdad's announcement is being treated with scepticism.

France and Russia have responded more favourably to the news.

The BBC's Richard Downes reporting from Baghdad

Russian Deputy Foreign Minister Viktor Posuvalyuk said his country believed the letter clearly said Iraq was agreeing to allow the UN inspectors to renew their normal work and "eliminates the possibility of using military force".

French President Jacques Chirac, visiting Mexico City, said the "pledges must now be put into practice".

Immediate return

Iraq's UN ambassador Nizar Hamdoon said the inspectors would be allowed to return immediately.

"They will be allowed any minute they want to to go back and to resume their normal work," he said.

"From now on it's up to them to decide when to go back."

A UN spokeswoman in Bahrain said the inspectors were awaiting word from New York on the latest developments.

She said the earliest they could return to Iraq was Sunday.

There are nearly 100 inspectors based in Bahrain, some of whom have returned to their home countries after they pulled out of Iraq.