ATLANTIC CITY, N.J. – The mayor of this gambling resort resigned yesterday after a two-week absence from office during which he checked himself into a rehabilitation clinic.

Robert Levy’s disappearance came amid a federal investigation for embellishing his Army service in Vietnam.

“Mr. Levy has concluded that public confidence is so eroded by these circumstances that the only responsible action is to step down,” said his attorney, Edwin Jacobs. “He does so with great regret and with apologies to his supporters, to the people of Atlantic City, and to his family and friends.”

The president of the seaside city’s council was sworn in as acting mayor.

City officials last heard from Levy on Sept. 26, when he called in sick, climbed into his city-issued Dodge Durango and seemingly vanished. Aides to Levy, a Democrat who took office in January 2006, would say only that he was hospitalized somewhere, and they would not disclose his condition.

Levy checked himself into a clinic because he had been overmedicating himself with pain pills to treat severe back pain, as well as using different medication to treat post-traumatic stress disorder stemming from his war service, Jacobs said.

“He needed to get off the medication he was taking. I wouldn’t call it an addiction. It was a detox situation,” Jacobs said.

Jacobs said he met with Levy on Sept. 23.

“It was apparent to me as a layman that he was experiencing medical problems. Bob Levy was in a medical crisis and needed a leave of absence,” Jacobs said at a news conference Wednesday that Levy did not attend.

The next day, according to Jacobs, he took Levy to a doctor who confirmed Levy had been overmedicating himself. Two days after that, on Sept. 26, Levy checked himself in to a center that treats substance abuse and mental health issues.

Details about the mayor’s whereabouts began emerging Tuesday, when Jacobs met with a judge considering a City Council request to declare Levy’s office vacant.