WASHINGTON — An American soldier is believed to be held by the Taliban after he walked off his base in eastern Afghanistan without his body armor and weapon, officials said Thursday.

The military has intercepted communications in which insurgents said they had captured an American, two U.S. officials said on condition of anonymity because they were not authorized to speak on the record.

Several officials declined to say whether there has been any direct communication with the insurgents or whether any demands had been made for the return of the soldier, who is a private first class. The military was largely silent about details surrounding the kidnapping, believed to be the first such abduction of a U.S. service member in the nearly 8-year-old war.

Officials said there were conflicting reports that the military was trying to sort out, including which Taliban insurgents may be holding him.

"We are not providing further details to protect the soldier's well-being," said Capt. Elizabeth Mathias, a spokeswoman in Afghanistan. Officials would not release his name or other details.

"We understand him to have been captured by militant forces," Mathias said. "We have all available resources out there looking for him and hopefully providing for his safe return."

U.S. troops were brought in from nearby areas to help with the search, which included helicopters, Afghan army support and increased use of intelligence gathering resources, officials said.