Palestinian officials Monday cleared Israel of responsibility in the death of the chief Hamas bombmaker, saying he was killed in a power struggle within the Islamic militant group.

Hamas rejected the findings, insisting Israel was responsible for the death of Mohiyedine Sharif. This meant it probably would not back away from threats to avenge Sharif's death by carrying out attacks in Israel."The story . . . about the assassination of Mohiyedine Sharif is not acceptable to Hamas," said Abdel Aziz Rantisi, a leading Hamas figure in the Gaza Strip.

Hamas leaders in Jordan accused the Palestinian Authority of fabricating evidence. Hamas "considers this as an attempt to harm the struggle of the Hamas movement, its martyrs and sacrifices," said a leaflet delivered to The Associated Press in Amman.

Sharif died March 29 at the scene of a car bombing in the West Bank town of Ramallah. Israel said he was killed in a premature explosion of a bomb intended for Israel. Palestinian officials said he was shot to death before the blast.

The case has strained ties between the Palestinian Authority and Hamas, which had been trying to find a way to co-exist. An open confrontation will make it easier for Palestinian leader Yasser Arafat to crack down on the militants, as demanded by Israel and the United States.

A Palestinian security official, speaking on condition of anonymity, said four Hamas members were under arrest in connection with the killing.

Jibril Rajoub, the Palestinian security chief in the West Bank, said the suspects included people whom Sharif had trained and others who had helped hide him.

"Today, it became clear from confessions that those who killed Mohiyedine Sharif were his colleagues who used to break bread with him," Rajoub said.

Tayeb Abdel Rahim, secretary-general of the Palestinian Authority, briefed Hamas leaders Monday on the results of the investigation.

Asked whether Israel had any role in Sharif's death, Abdel Rahim said: "The case is one of individuals. No state is behind this case. This is what we have proven."

Israeli Prime Minister Benjamin Netanyahu said Abdel Rahim's announcement was "a positive development" and proved Israel's repeated assertions that it was not involved.