Britain has received a request from the United States for help from UK troops in Iraq - and the Chief of the Defence Staff is expected to recommend whether to comply by the middle of this week, Defence Secretary Geoff Hoon announced today.
Mr Hoon told MPs the British troops would not be required to serve in Baghdad or Fallujah.
The Defence Secretary said no decisions had yet been made and a UK reconnaissance team will be going to the relevant area - not named by Mr Hoon - tomorrow to gather information for the Chiefs of Staff.
Mr Hoon stressed: "The request is a military request."
It was not linked to the US elections but the Iraqi elections, scheduled for January.
Mr Hoon told MPs: "There has been considerable speculation in the media over the past several days about the United Kingdom deploying forces outside its current area of operations in southern Iraq.
"The only relevant fact is that the UK military received a request on October 10 from the US military command in Iraq for assistance.
"Such requests and discussions between allies are routine."
The Defence Secretary said this request, if agreed to, would involve UK land forces being deployed outside their normal operating area around Basra.
This was not the first time this had happened and some UK military personnel are already based in Baghdad to support coalition areas, said Mr Hoon.
He went on: "Iraqi security forces and coalition forces have recently been involved in intensified operations to restore areas under the control of militants and terrorists to the authority of the Iraqi interim government.
"Recent operations in Najaf, in Samarra, and in North Babil have been undertaken as part of this effort.
"The political process is moving ahead as a result of these actions. This strategy is designed to increase presure on and deal with those terrorists who are trying to prevent the rebuilding of Iraq, and who threaten the holding of free elections in January.
"The US request is for a limited number of UK ground forces to be made available to relieve US forces to allow them in turn to participate in further operations elsewhere in Iraq to maintain the continuing pressure on terrorists.
"The request does not ask for British troops to be deployed to Baghdad city, nor to Fallujah."
Mr Hoon said the request was being considered, along with details such as the length of the operation, its timing, command and control arrangements and which forces would be the most appropriate to conduct the operation.
Chief of the Defence Staff General Sir Michael Walker would make his final recommendation by the middle of the week, said Mr Hoon.
Mr Hoon refused specifically to confirm that the UK troops involved would come from the Black Watch regiment, currently serving as the reserve in the UK area of operations.
But he responded several times to MPs' questions asking if the regiment would have to stay beyond its routine six–month tour of duty, scheduled to finish by the end of the year.
He said the Black Watch were "determined to carry through this operation, should it be decided they participate".
Mr Hoon said some members of the regiment might have been informally told they would return home early from their six–month tour and would now not be if they were chosen to take on the new role.
But he said he had no doubt about the regiment's morale. When he inquired, he said, he was told: "I, for one, could take my criticisms and put them somewhere else. I paraphrase."
Shadow defence secretary Nicholas Soames and ex–Tory leader Iain Duncan Smith asked whether British troops operating under American rules of engagement could be subject to prosecution under International Criminal Court rules.
Mr Hoon refused to discuss details of the troops' rules of engagement but said ICC action would only ever be taken where the soldiers' own country would not take action.
"We would take action," said the Defence Secretary.