Afghan President Hamid Karzai is due to begin a four-day US trip Tuesday in which he will meet US President Barack Obama for crucial talks on the future of the American presence in Afghanistan.

Friday's meeting at the White House will come just days after Obama put the finishing touches to his security team, having named his picks to head up the State Department, Pentagon and CIA.

Officials have said a decision could be made during Karzai's official visit on how many US troops will stay in Afghanistan after 2014.

Talks with high-ranking US officials will focus on security, economic and political transition, equipping and strengthening Afghan forces, efforts to negotiate peace with Taliban-led insurgents and a security agreement with the United States, Karzai's office said.

The Afghan leader, who left Kabul on Monday, is due to meet with Secretary of State Hillary Clinton on Thursday.

He is also expected to kick off his US trip by visiting his wounded spy chief, Asadullah Khalid, at an American hospital on Tuesday.

Obama looks forward to "discussing our continued transition in Afghanistan, and our shared vision of an enduring partnership between the United States and Afghanistan," a White House statement said.

The Afghan leader has expressed support for keeping US troops in Afghanistan but sensitive details -- including immunity for American soldiers and the transfer of detainees into Afghan custody -- are still under negotiation.

Karzai's relationship with Washington has been troubled in recent years and there are fears that attention for Afghanistan, heavily dependent on international aid, could plummet after 2014, plunging it back into political turmoil.

The US Defense Department has reportedly prepared plans to leave roughly 3,000, 6,000 or 9,000 US troops in the war-wracked state.

General John Allen, commander of US and NATO forces in Afghanistan, had earlier suggested leaving 6,000 to 20,000 US troops, US media reports have said.

Outgoing Defense Secretary Leon Panetta has said the force would focus on preventing Al-Qaeda, which was sheltered by the 1996-2001 Taliban government, from regaining a firm foothold in Afghanistan.

The number of foreign troops battling the Taliban-led insurgency has already fallen to 100,000 from about 150,000. Of those, 66,000 are US troops, down from a maximum of about 100,000.

Karzai has suggested his government is ready to agree to demands for legal protection of US troops after 2014.