A former CIA contract employe was arrested by the FBI in New York yesterday on charges that he provided classified national security information to the Czechoslovakian Intelligence Service (CIS).

There was no description of the material he may have provided.

FBI Director William H. Webster said Karl F. Koecher, 50, a naturalized U.S. citizen, worked for 19 years in the United States as a spy for the CIS and lived until recently in New York City.

Koecher was charged with delivering defense information to aid a foreign government. He was to be arraigned this morning in U.S. District Court in Manhattan. If convicted, he could face life in prison.

Koecher's wife, Hana, 40, was described in court papers as a courier for the CIS between 1974 and 1983. She was held as a material witness in the case, but was not charged.

The FBI said Koecher was born in Czechoslovakia and was trained by the CIS from 1963 to 1965 as an intelligence officer. Koecher entered the United States in 1965 with his wife, and later became a citizen, the bureau said.

Although the FBI provided few details, it said that Koecher served as an "illegal officer" of the CIS since his entry into the United States in 1965 and that he had been directed by the CIS to infiltrate "through employment any U.S. intelligence agency."

The bureau said Koecher worked for the CIA from February 1973 until August 1975 as a "support or contract" employe who had a security clearance with access to classified national security information.

Webster said the arrest followed an extensive FBI investigation. FBI officials refused to provide details of Koecher's activities during the time he was not employed by the CIA.

A CIA spokesman said the agency would not elaborate on Koecher's duties, where he worked or why he left his CIA job.

An affidavit filed in U.S. District Court in Manhattan said Koecher and his wife were arrested yesterday afternoon at their New York apartment, which they sold on Monday. They were scheduled to leave New York last night on a flight for Zurich, Switzerland, the court papers said, and "intended to reside in Austria."

Rudolph Giuliani, U.S. attorney for the Southern District of New York, said Koecher was arrested yesterday because the FBI was aware that he intended to leave the country. "We strung it out as long as we could to gain as much evidence as possible," Giuliani said. "It was timed so we could grab them as they were leaving the house for the airport."

Koecher is the third former CIA employe charged with spying for the Soviet bloc in recent years. And last month the FBI arrested the first of its agents ever charged with spying for a foreign government.