The information chief of the Palestine Liberation Organization was killed yesterday by a bomb that exploded under his bed in one of Rome's most luxurious hotels.

Police said it was a highly professional assassination. Majed Abu Sharar, chief of the PLO's public relations department, died when the bomb went off shortly before 1 a.m. (8 p.m. EDT Thursday) in his room on the fourth floor of the Flora Hotel on the Italian capital's Via Veneto.

A PLO spokesman blamed Israel for the attack, calling Abu Sharar a victim of the "homicidal madness of Israeli terrorists."

However, a hard-line Palestinian group in Beirut claimed responsibility for the assassination, saying it killed Abu Sharar because he had "diverged" from the radical line and had become too moderate.

The bomb started a fire that burned Abu Sharar's corpse beyond recognition and forced scores of tourists and other hotel guests to flee their rooms in nightclothes. Firemen quickly extinguished the blaze and experts said they found evidence the bomb was rigged under the bed.

A bomb blast on Thursday damaged an Israeli tourist office only two blocks from the Flora Hotel.

Abu Sharar was registered at the hotel as Abbas Zithouni, 47, an Algerian living in Beirut. A spokesman for the PLO's Rome office conceded Zithouni was really Abu Sharar, a member of the central committee of Al Fatah, the PLO guerrilla group headed by Yasser Arafat. The spokesman said Sharar, in Rome for a conference of Arab journalists, carried the Algerian passport as a security precaution.

Al Assifa, a pro-Syrian guerrilla group, telephoned new agencies in Beirut and Rome to claim responsibility for the killing. "In the same way we killed Abu Sharar, we will kill all others who seek to compromise the principles of our revolution," it said.