Washington  - The top US military commander for Afghanistan warned that he needs additional troops within the next 12 months or the conflict will "likely result in failure," the Washington Post reported Monday.

The assessment by General Stanley McChrystal, is outlined in a 66-page report sent to Defence Secretary Robert Gates on August 30, a copy of which was obtained by the Post.

"Failure to gain the initiative and reverse insurgent momentum in the near-term (next 12 months) - while Afghan security capacity matures - risks an outcome where defeating the insurgency is no longer possible."

On Wednesday, Obama said he had not yet made any decision on sending additional US troops to Afghanistan, despite some calls for more resources from military commanders.

The president said he was still conducting a full review of the administration's Afghanistan strategy and was closely watching the aftermath of the country's disputed presidential election.

"There is no immediate decision pending on resources, because one of the things that I'm absolutely clear about is you have to get the strategy right and then make determinations about resources," Obama said after a meeting with Canadian Prime Minister Stephen Harper.

Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, told a Senate committee Tuesday that more troops were needed to train Afghan forces to maintain security.

Obama said last week that McChrystal's report was just one component of his strategy.

"General McChrystal has carried out his own assessment on the military strategy, but it's important that we also do an assessment on the civilian side, the diplomatic side, the development side, that we analyze the results of the election and then make further decisions moving forward," Obama said.

In his report, McChrystal detailed the growing Taliban insurgency as well as the rampant corruption in the Afghan government.

He said repeatedly that unless he is given more troops and a stronger counterinsurgency strategy, the eight-year war in Afghanistan will be lost.

However, McChrystal's report also concludes that "while the situation is serious, success is still achievable."

Obama has already ordered one troop escalation since coming into office. The US boosted its forces by 17,000 combat troops and 4,000 trainers to work with the Afghan military. The last of those additional forces will be on the ground by the end of the month.

Pentagon officials said McChrystal was expected to propose an additional 10,000 to 45,000 troops for Afghanistan, the New York Times reported. (dpa)