An air and ground search continues for two U.S. navy service members who disappeared in eastern Afghanistan amid unconfirmed reports that one or both were captured by the Taliban.

The two failed to report back after leaving their compound in Kabul on Friday afternoon, NATO officials said. Vehicles and helicopters have been sent to search for the two.

Afghan National Police officials reported seeing two U.S. soldiers driving around in an armoured vehicle in the nearby province of Logar. Police said they tried to wave down the Americans but they drove on and went into a bazaar, CBC's Cameron MacIntosh reported from Afghanistan.

Officials say the two were later ambushed by insurgents as they tried to drive away.

MacIntosh said local reports are conflicting, with some suggesting the Taliban have claimed they abducted both Americans and other reports saying one American may have been captured and the other killed.

NATO will not verify the reports relating to the claims of the Taliban or the Afghan police, saying only that it’s looking for its missing people. But the U.S. is broadcasting local radio ads offering a $20,000 US reward for the return of two members.

The Taliban have exaggerated reports of kidnapping Americans in the past, MacIntosh said.

Specialist Bowe Bergdahl of Hailey, Idaho, was captured by the Taliban in June 2009. He is the only known American in the Taliban's hands and has appeared in videos posted on Taliban websites.

The disappearance of the navy service members comes after five U.S. troops died in roadside bombings in the south — four in a single blast. A fifth service member was killed in a separate attack in the south where international forces are stepping up the fight against insurgents.

With files from The Associated Press