Britain's army chief has earmarked extra troops to send to Afghanistan, The Times newspaper reported Friday as US President Barack Obama prepared to unveil a new strategy for the war there. General Richard Dannatt, the chief of the general staff, told the paper that elements of 12 Mechanised Brigade had been "earmarked for Afghanistan". He said there were no plans to send all the brigade's 4,000 troops, but the increase could take the total number to "somewhere in between" the 8,000 now deployed and the 12,000 that would result from the whole brigade being sent. The move -- which is subject to approval by the government -- comes amid fears that the US-led mission will struggle without significant reinforcements, The Times said. Obama is expected to announce his strategy for Afghanistan on Friday, after a two-month top-to-bottom review of the war effort. Defence officials said the president was planning to send an extra 4,000 troops to train Afghan security forces later this year, on top of the 17,000 reinforcements to take on Taliban and allied insurgents announced last month.