JERUSALEM - Israel obtained a two-decade-old letter written in captivity by its most famous missing soldier as part of a recent exchange with the Hezbollah guerrilla group, Prime Minister Ehud Olmert said Monday.

The letter from Ron Arad, a navigator who abandoned his Phantom jet over Lebanon in 1986 and whose fate is unknown, was turned over last week as part of a deal in which Israel returned a mentally ill Hezbollah man and two fighters' bodies in return for the body of an Israeli who drowned in the Mediterranean and washed up in Lebanon.

Speaking to reporters in France, where he is on a state visit, Olmert called the letter from Arad "moving,'' but said he hadn't read it because it was personal. The statements by Olmert were reported by Israeli media and confirmed by his spokeswoman, Miri Eisin.

The letter was written by Arad to his wife, Tami, not long after he went down over Lebanon, and was accompanied by a photograph, according to a report Monday in the daily Yediot Ahronot.

Tami Arad was summoned to the Defence Ministry after last week's exchange and given the letter, the report said. She recognized the handwriting and the pet names her husband used to refer to her, and after reading the letter she "fell apart,'' the paper reported.

Arad was forced to parachute out of his fighter jet on a mission over Lebanon in October 1986 after one of his aircraft's bombs apparently malfunctioned. The jet's pilot was rescued by Israeli forces, but Arad was captured by guerrillas from the Shiite Amal organization.

Letters and photographs from Arad were initially sent to Israel, but talks for his release failed not long afterward and the navigator was not heard from again. In addition to his wife, he left an infant daughter in Israel.

There have been reports that Arad had been transferred to Hezbollah fighters and then to Iran, but no reliable evidence of his fate has ever surfaced. His family has waged a 21-year battle for information, pressuring Israeli leaders not to give up on finding him.

Hezbollah's leader, Hassan Nasrallah, said last year that he believes Arad is dead. But Israel has said it is working under the assumption he is alive and will continue the search until it has proof to the contrary.

Hezbollah is now holding two Israeli soldiers it captured in July 2006 in an incident that sparked a 34-day war between the militant group and Israel. Hezbollah has not allowed the Red Cross to see them, and it is not known whether the soldiers are alive or dead.

Israel is thought to be holding seven Lebanese prisoners.

Talks of a new prisoner swap to bring home the two captured soldiers have not yielded any results so far. But after last week's UN-mediated exchange, Hezbollah leader Hassan Nasrallah said Tuesday there is "positive progress'' in negotiations.