KUWAIT CITY (AP) _ The PLO headquarters in Kuwait City was sprayed with automatic rifle fire Tuesday by a uniformed man in a security force vehicle, the latest in a series of attacks on Palestinians since Kuwait's liberation six weeks ago.

Members of the Palestinian Liberation Organization inside the building, which they consider their embassy, said they had been harassed frequently but had not come under attack before.

U.S. diplomats and human rights groups have expressed concern about reports that vigilantes and rogue elements of the security forces have been killing, beating and arbitrarily detaining Palestinians suspected of supporting the Iraqi occupation of Kuwait.

The attack on the PLO office was carried out by one of two men wearing Kuwaiti military uniforms and traveling in a white Nissan pickup truck equipped with rooftop police lights.

They drove past the PLO office and stopped by a street corner where a PLO member was talking with an Associated Press reporter.

The men asked for the Palestinian's identity card, and one leapt from the vehicle when the Palestinian said the card was at another location.

The Palestinian then sprinted inside the office.

''The next time I see him I'll kill him,'' the uniformed man said. He gestured toward the PLO office, and said: ''This place is rubbish.''

The pickup truck drove away, then returned moments later, and the same man got out by the PLO office and began firing an M-16 rifle at the building.

He got back in the truck and resumed firing as his partner drove away. About 10 shots were fired in all. No one was injured.

Inside, about 12 Palestinians gathered behind drawn curtains and a bolted door to discuss the attack.

''I think they expect us to shoot against them, then they will bring more soldiers,'' one man said.

The office is in a dilapidated stucco building in Hawalli, a Palestinian neighborhood. Trash litters nearby streets and the smell of sewage is pervasive.

The Palestinian who was accosted on the street corner, who asked to be identified by his code name of Bayar, said the PLO and the emirate's 400,000 Palestinians had enjoyed cordial relations with Kuwaiti authorities and civilians before the Iraqi invasion.

''Now, hardly any Palestinians want to stay here,'' he said. ''It's not like before.''

The Palestinian community feels it has been unfairly singled out for revenge attacks because some Palestinians collaborated with the Iraqis.

Last week, a prominent Palestinian dentist, Saleem Muktar, was shot to death near an army checkpoint. But no arrests have been reported in that case or any of the other attacks on Palestinians.

On Monday, Kuwait's minister of Cabinet affairs, Abdullrahman al-Awadi, told reporters that no regular security force members have orders to harass or brutalize Palestinians. He said the government was concerned about the reports of abuses and was ''very sensitive to the Palestinian cause.''

The Kuwait Association to Defend War Victims, a private group attempting to account for several thousand missing Kuwaitis, said Tuesday most of the reports of people who disappeared since liberation involve Palestinians.

Kuwaiti authorities are preparing cases against suspected war criminals and Iraqi collaborators, and many of the 628 people being held are believed to be Palestinians.

Abdul Aziz al-Dakhil, the undersecretary of justice, said Monday the trials could begin within weeks.