The US military will keep providing logistical support in villages as it hands over the security lead to Afghan forces this spring, Afghanistan's envoy to Washington said Monday.

US President Barack Obama and Afghan President Hamid Karzai announced Friday that the United States would speed up the transfer of security responsibility, preparing for the withdrawal of US combat forces by the end of 2014.

In a joint news conference at the White House, Karzai said Afghan forces would be fully responsible for protection by spring and that "the American forces will be no longer be present in Afghan villages."

Ambassador Eklil Hakimi, addressing reporters in Washington in the wake of Karzai's visit, clarified that US forces would still be present but in a supporting role.

"We still need the logistical support and other support from coalition forces. So now would be a joint operation with Afghans to be in the lead, with the support that we receive from your side," he said.

Hakimi said the two governments and military leaders would work out the exact number of troops to stay after 2014 when the United States withdraws its 66,000 combat troops from Afghanistan, ending its longest war.

The Obama administration has proposed troops levels as low as several thousand and said it was open to leaving no troops at all in Afghanistan, although experts see such statements as partially a negotiating strategy.

The United States is pressing for Afghanistan to grant all its remaining troops immunity from local courts, an issue that scuttled proposals to keep a residual US force in Iraq.