Jason Rezaian, The Washington Post’s former bureau chief in Tehran whose 544-day imprisonment in Iran during the nuclear negotiations aggravated tense relations with the United States, filed a federal lawsuit Monday against the Iranian government, accusing it of hostage-taking, torture and terrorism.

The 68-page lawsuit, filed in federal court in Washington, contained many previously undisclosed details of Mr. Rezaian’s travails in the Iranian penal system, including a 50-pound weight loss, thoughts of suicide and threats by his captors to dismember him and his wife, and throw him off a cliff.

The suit, which also lists his family as plaintiffs, essentially accused the Iranian authorities of having used Mr. Rezaian as leverage in the nuclear negotiations because they regarded him as a high-value prisoner who could be swapped for something they wanted.

It is at least the second federal lawsuit against Iran filed by Americans who were released by the Tehran government when the nuclear agreement took effect in January. The pact relaxed some sanctions on Iran in exchange for reduced nuclear activities.