A possible imminent terrorist attack and the arrests of about a dozen people, some with possible links to fugitive Saudi businessman Osama bin Laden, prompted a State Department warning to Americans abroad, senior U.S. officials said late yesterday.

The arrests were made in a Middle Eastern country and involved advanced planning for one or more terrorist attacks expected to coincide with year 2000 celebrations, said officials, who spoke on condition of anonymity.

Targets for the attacks were not clear, but they appeared likely to involve Americans overseas, the officials said. One official said the information was "one of the factors that went into the State Department decision to issue the warning over the weekend."

The State Department on Saturday warned Americans living or traveling abroad to take extra precautions between now and the first week in January.

The warning cited "credible information" that terrorists were planning attacks "specifically targeting American citizens." It suggested locations where there would be large gatherings and celebrations as likely targets.

State Department spokesman James B. Foley said yesterday that it was "our obligation when we become aware of information that may impact on the travel and the safety of Americans to share that with the public."

He said the threats were connected to the New Year celebrations and Ramadan, the Islamic period of fasting. "We're not being specific about the exact nature of the threat because this is something which is under investigation," Foley continued.

One official said that the arrests were "a local operation" and that the U.S. government did not participate. This official and others refused to identify the country where the arrests took place, other than to say it was in the Middle East.

It was not clear whether those who were arrested would be held and charged, said the official.

"Associates of bin Laden appear to be involved in planning some sorts of attacks in relation to the end of the year," the official said.

Bin Laden has been indicted by a New York grand jury on charges of conspiracy and murder in the 1998 bombings of U.S. embassies in Kenya and Tanzania, which killed 220 people. He is living in Afghanistan under the protection of the ruling Taliban militia.