French police arrested former CIA official Philip Agee in Boulogne last night and ordered him expelled to Belgium, the government announced today.

The presence of the apostate agent, who quit the Central Intelligence Agency in 1969 and wrote a book identifying co-workers and exposing covert American operations, was "undesirable" and could harm France's relations with "friendly countries," the announcement said.

A spokesman for the American embassy denied that the United States had discussed Agee's presence here with the French or brought any pressure to get him expelled. "It is purely a French decision," the spokesman said.

The 41-year-old former undercover operative was expelled from Britain in June after a six-month court battle to keep his residence there. He had lived in Britain for four years before his expulsion as a security risk. Information supplied by Agee's French lawyer indicated that British and French police cooperated in yesterday's action.

The lawyer, Jean-Michel Braunschweig, said late today that he has not been able to confirm that Agee had actually been expelled from French territory, although the announcement from the Interior Ministry referred to the expulsion as having already taken place. "We are getting a runaround on his presence," the lawyer said.

Agee, evidently traveling under his own name, arrive in France three weeks ago on a tourist visa valid for three months. He has been living in the Netherlands, where he is seeking a residence permit to enable him to finish his second book on the CIA.

In an interview in this week's edition of Newsweek International, which went on sale here just 24 hours before his arrest, Agee vowed to continue exposing organizations and people with CIA associations, and indicated that his next book would deal in detail with the agency's work in Europe.

Agee traveled from Paris to Boulogne yesterday to meet Angela Camargo-Seixas, a Brazilian with whom he lived in Britain. She was arriving by boat from Britain. French police were waiting for her and immediately took her into custody when she landed at Boulogne, Braunschweig said. She was released after Agee had been detained by frontier police.

Agee's book, "Inside the Company: CIA's Diary," was published in translation here two years ago. Agee said in the interview with Newsweek, and the American embassy confirmed, that there are outstanding charges against him the United States.