US investigators in Iraq found the initials of navy pilot Michael Scott Speicher etched into a prison wall in Baghdad, officials said. Intelligence officials from Saddam Hussein's regime captured on Wednesday night may provide further clues.

A team of officials from the CIA and the defence intelligence agency searching for clues to Speicher's fate found the letters MSS on a cell wall in the Hakmiya prison. The officials said an informant had reported that a US pilot was held there in the mid-1990s.

Cindy Laquidara, a lawyer for the Speicher family, said close relatives were "very excited" and remain convinced he is alive.

Speicher, an F/A-18 Hornet pilot from Jacksonville, Florida, and three other pilots flew off the USS Saratoga for a bombing run over Iraq on January 17 1991, the first night of the war. The US defence department said his plane had been downed by an Iraqi missile. The Pentagon classified the pilot as killed in action, changed last year to "missing in action, captured".

Iraqi officials said Speicher had been killed. But there have been persistent intelligence reports about a US pilot held in Baghdad.The captured former head of Saddam's military intelligence may yield clues to his fate.