AFP - British Prime Minister Gordon Brown has upped the pressure on Afghan President Hamid Karzai insisting he draw up in the next two months an action plan to enable foreign forces to start withdrawing.

Karzai needed to draw up a "credible plan" for international forces to start handing over control to Afghan military and police before an international conference in London on January 28, Brown told Sky News in Trinidad.

"I want to know that by the time we get to January 28 we have a credible plan in place from President Karzai so that we can train Afghan troops," Brown said in the interview late Saturday.

Brown earlier revealed that the London conference would bring together the major stake-holders in the Afghan conflict, with the exception of Taliban insurgents.

Karzai, UN chief Ban Ki-moon and major contributors to the coalition fighting in Afghanistan including the United States as well as regional neighbors will be invited to talks.

Karzai has to realize "that there will be milestones by which he's going to be judged and he's got to accept that there will be benchmarks which the international community will set," Brown told journalists, as he unveiled his plan on the sidelines of a Commonwealth summit here.

The January conference, which has also been backed by German Chancellor Angela Merkel, won swift support from Washington which already has 68,000 troops in Afghanistan.

"The United States looks forward to contributing to the development of a substantive agenda that will advance our collective efforts in Afghanistan," Mike Hammer, National Security Council spokesman, told AFP.

US President Barack Obama is to unveil a new strategy on Afghanistan on Tuesday. He is expected to commit more than 30,000 fresh US troops to the conflict now in its ninth year.

But the US leader, who has vowed to "finish the job" in Afghanistan, will also lay out an exit strategy.

Brown said the aim was to draw up clear benchmarks for future military and political strategy in Afghanistan for 2010 and beyond.

He plans to build up the Afghan security forces to 50,000, and committed Britain to training 5,000 more in Helmand province alone by the end of 2010.

The British leader also called for 5,000 more troops from other countries outside of Britain and the United States to be deployed with NATO's International Security Assistance Force (ISAF).

He told Sky he wanted to set Karzai a series of three-monthly targets so that international forces can start to hand over control of Afghanistan.

Three months after the January talks "I feel we should also have a credible plan about how he's going to reform the police service in Afghanistan -- there are many allegations about its corruption and its ineffectiveness and we want to know that things are being done there.

"Within six months, I think he's got to have appointed the district and provincial governors," Brown said, adding that some of the appointments "have got to be looked at very carefully."

The aim is to gradually hand over responsibility for security to Afghan forces, district by district and province by province, enabling Britain to begin withdrawing its 25,000 troops.

"I want the conference in London to set the conditions needed for district by district handover to Afghan lead responsibility (for security)," Brown said.

He stressed that a timetable for withdrawing British forces from the increasingly unpopular war would only be drafted once the Afghan army and police show they can maintain security.

At least 483 foreign troops, about half of them Americans and some 98 Britons, have been killed in Afghanistan this year, according to the icasualties.org website, making it one of the deadliest years for troops since the US-led invasion in 2001.

The hope is that one or two districts in restive southern Helmand province could be transferred in 2010 to Afghan forces, and up to five Afghan provinces by the end of the year, Brown said.