PARIS  A former Guantánamo detainee, an Algerian given a new home in France, is contending that he was interrogated at the Cuban detention center for 16 straight nights in 2003  from midnight until 5 a.m., at least  and that he was force-fed through a nasal tube for more than two years when he went on a hunger strike.

The Algerian, Lakhdar Boumediene, 43, is the only Guantánamo detainee that President Nicolas Sarkozy of France has agreed to accept so far to help the Obama administration close the detention center.

Mr. Boumediene was captured in 2001 in Bosnia and handed over to American officials. He was kept at Guantánamo from January 2002 until May 15 of this year as terrorism suspect No. 10005, when he was released and put aboard a plane to France. He was kept under observation in a French military clinic until Monday, when he emerged and told some of the details of his story to The Washington Post and Le Monde, which published them on Tuesday.

No. 10005 “was my name there,” he said. “That’s what they called me. Never Lakhdar or Boumediene,” he told Le Monde.