KIGALI, Rwanda (AP) _ Hutus armed with assault rifles and machetes hunted down hundreds of Tutsis who had sought refuge in a Zairian church and slaughtered at least 12 of them, a U.N. official said today.

About 130 other Zairian Tutsis who had been hiding in the church were missing, and by late Wednesday at least 600 others had fled the armed mobs to Kichanga, near the border with Rwanda, said Paul Stromberg, spokesman for the U.N. High Commissioner for Refugees.

A U.N. team has gone up to assess the situation and see how the United Nations can help, Stromberg said.

The attack on the church, he said, was reminiscent of the 1994 massacres of 500,000 people, most of them Tutsis, in Rwanda. During the genocide, thousands of Tutsis took shelter in churches to avoid government-sponsored mobs. But most were massacred inside the churches.

Stromberg said at least 800 Zairian Tutsis had sought shelter at a French-run church in Mokoto village in remote eastern Zaire after armed Rwandan Hutu refugees drove them from their homes.

Fighting around the church, 60 miles north of the Zairian border town of Goma, intensified last week, forcing the French priests to leave Mokoto for Goma on Sunday. Mobs of Hutus who have been living in Zaire for years and more recent Rwandan Hutus from nearby refugee camps reportedly attacked the church after the priests left, Stromberg said.

More than 1 million Rwandan Hutus have been living in exile in eastern Zaire since Rwandan Tutsi rebels toppled their country's Hutu government in 1994 and ended the Hutu genocide of Rwanda's Tutsis.

The Hutu refugees refuse to return home, fearing reprisals for the massacres. Since arriving in Zaire, they have been attacking Zairian Tutsis, too, in an effort to take their land.

Both groups came to Zaire from Rwanda, beginning decades ago, but have not traditionally clashed.

The government of Rwanda accuses the international community of ignoring the mass killings of Tutsis in eastern Zaire. There has been no independent confirmation, but several hundred have been reported killed.

Zairian Tutsis who have fled to Rwanda say Rwandan Hutu refugees have joined with Zairian Hutus to create a ``Hutuland'' by forcing other ethnic groups out of eastern Zaire.

More than 9,600 Zairian Tutsis have fled to Rwanda since March 27 and more than 350,000 other people have been displaced inside Zaire.

On Wednesday, President Pasteur Bizimungu of Rwanda called on world leaders to take immediate action in Zaire to ensure the safety of minority ethnic groups and to pressure Zaire to stop the flow of Zairian Tutsi refugees into Rwanda.