KABUL (Reuters) - A suicide bomber killed 14 people, including three NATO soldiers and four police, and wounded 37 in Afghanistan's volatile eastern Khost province on Monday, a NATO spokeswoman and local officials said.

A U.S. official in Washington confirmed the three soldiers killed were Americans serving in the NATO-led International Security Assistance Force. Six civilians and an Afghan interpreter also died in the attack.

A witness told Reuters a suicide bomber wearing a police uniform struck as U.S. soldiers patrolled the city of Khost. A NATO spokeswoman confirmed only that the attack was carried out by a suicide bomber.

Provincial Governor Abdul Jabar Nahimi said the bomber had been riding a motorcycle packed with explosives and 37 civilians were wounded in the blast.

The Afghan Taliban claimed responsibility, although Afghan insurgents are quick to claim any successful attack on foreign troops as their own.

The bombing followed the killing of two Americans on Sunday in an exchange of fire with Afghan forces that took the death toll of U.S. military and civilian personnel to over 2,000 in the 11-year war.

Insider attacks by members of the Afghan security forces against NATO allies have resulted in 52 deaths this year among foreign forces and this month prompted a tightening of rules for joint patrols between coalition and Afghan forces.

A U.S. official in Washington confirmed the deaths of the three American soldiers.

(Reporting by Elyas Wahdat; Additional reporting by David Alexander in Washington; Writing by Rob Taylor; Editing by Nick Macfie and Jackie Frank)