President Barack Obama offered his Afghan counterpart Hamid Karzai additional US assistance Sunday to relief efforts after a landslide killed hundreds of people in northern Afghanistan.

Much of Aab Bareek village in Badakhshan province was swallowed on Friday by a fast-moving tide of mud and rock that swept down the hillside and left almost no trace of hundreds of homes.

At least 300 were killed, and officials warned the death toll could rise by hundreds more. A total of 700 families were left homeless in the mountains.

During a phone call between the two presidents, Obama "affirmed the support of the American people as the Afghans respond to this tragedy and offered additional US assistance to the ongoing relief efforts," a White House statement said.

He also expressed his condolences for the "extensive" loss of life.

And addressing last month's election, with a run-off vote between frontrunner Abdullah Abdullah and ex-World Bank economist Ashraf Ghani due June 7, Obama "reaffirmed that the United States supports a sovereign, stable, unified and democratic Afghanistan."