JERUSALEM (AP) _ Arab gunmen forced their way into a hospital in the occupied West Bank at dawn Thursday and assassinated a Palestinian suspected of collaborating with Israel.

Arab reports said the squad used a gun with a silencer to kill 55-year-old Taleb Yamin. He was hospitalized after an attack last week in which he was beaten and stabbed.

In a second slaying, a Palestinian suspected of cooperating with Israeli authorities was shot in the head by Arab attackers.

Arab reports said the victim, 48-year-old Fayel Fawalha, was given first aid by Israeli soldiers and evacuated by an army helicopter. The army said Fawalha died later at Israel's Tel Hashomer Hospital.

Also Thursday, a 13-year-old Palestinian boy was shot and killed by a military patrol, Arab hospital officials said. Arab reports said there were no clashes between troops and Palestinian stone-throwers at the time, and that it was not clear what provoked the shooting.

All three shootings occurred in the West Bank town of Nablus.

The army spokeswoman confirmed the slayings of the men and said police were investigating. She said officials were checking reports of the boy's death.

Foreign Minister Moshe Arens termed the attacks the latest examples of a PLO ''reign of terror'' in the occupied West Bank and Gaza Strip.

He also said Israel considers the U.S. dialogue with the PLO as encouragement to the PLO and an impediment to peace. The PLO-U.S. talks resumed Thursday in Tunis.

''The PLO is the obstacle to peace in the region,'' Arens said on Israel radio. ''Talking with them gives them a feeling of legitimacy and recognition and makes the peace process more difficult.''

In the fatal attack at Rafidiyeh Hospital, ''a group of people entered the hospital at 5 a.m.,'' said Dr. Abdel Rahman Shinar, the hospital's director. ''They forced a male nurse and a relative to leave the room. Then they opened fire, killing him instantly.''

Another doctor, who spoke on condition of anonymity, said Yamin was shot once in the head. Arab reports said the gang was armed with a gun with a silencer.

The slayings of the men brought to 50 the number of Palestinians killed by other Arabs since the uprising against Israeli rule in the occupied territories began in December 1987. Most have been accused of helping Israeli authorities or of drug dealing or prostitution.

All three deaths brought to 512 the number of Palestinians killed in the 18-month-old rebellion, most in clashes with Israeli soldiers. Twenty-two Israelis also have died.

In the Gaza Strip, Israeli soldiers on Thursday sealed the homes of three Palestinians accused of throwing firebombs at troops.

A day earlier, the army blew up one house and sealed another belonging to Palestinians suspected in firebomb attacks.

The United States and human rights groups have denounced the practice, saying it violates the right to due process because those punished usually have not been charged or tried.

An 18-year-old Palestinian was reported wounded in the leg in a clash with troops in Jebaliya in the Gaza Strip, which remained under curfew for the fifth consecutive day.

The curfew was lifted for two hours Thursday to allow the strip's 700,000 residents to buy food.

Meanwhile, Vice President Dan Quayle urged Israel to halt all settlement activity in the occupied lands, and suggested that even talking about such plans was harmful to peace.

''These announcements of new settlements are politically problematic even if they don't go through with it,'' Quayle said in an interview with the English-language Jerusalem Post newspaper.

''It's something I wish there was a sensitivity to,'' he said.

In an unusually blunt speech last month, Secretary of State James A. Baker III lashed out at the settlements, saying they were a bar to peace.

More than 130 settlements housing about 70,000 Jews have been built in the territories, home to 1.7 million Palestinians.

A public opinion survey published Thursday indicated 53 percent of Israelis would object to dismantling the settlements as part of a peace agreement. But 42 percent of the 579 respondents favored their removal.

The poll was conducted this week by the Dahaf Institute and carried in the Yediot Ahronot daily. No margin of error for the poll was given.