The British military death toll in Afghanistan and Iraq reached the grim milestone of 300 when two Royal Marines were killed in Helmand province.
The pair, who were serving with the UK Landing Force Command Support Group, died on Wednesday afternoon when their vehicle was struck by an explosive device in the Garmsir district of southern Helmand.
Their deaths brought the total killed in Afghanistan to 124, while 176 have died on active service in Iraq since operations began.
The news came as Prime Minister Gordon Brown and Afghan President Hamid Karzai met in London to discuss the strategic situation in the region, with economic problems and unrest growing in neighbouring Pakistan.
Downing Street said Mr Karzai had praised the work of British troops and expressed "condolences" over the deaths when he met Mr Brown.
US president-elect Barack Obama is planning to send two more combat brigades to Afghanistan and is expected to call on other Nato allies to beef up their own deployments when he takes office in January.
But Number 10 stressed that the talks had focused on how the UK's support operations in Afghanistan could be enhanced rather than the possibility of more troops being sent.
When it was put to the Prime Minister's spokesman that extra forces were set to be deployed, he responded: "I don't agree with the assertion that we now look like we are sending more troops."
A recent ICM poll for BBC Radio 4 found more than two-thirds of the public believe all British troops should be withdrawn from the troubled country in the next year.
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But the spokesman rejected suggestions the UK public was not behind the campaign. He said research carried out by Mori for the MoD had indicated more than half the population supported the military presence in Afghanistan.
