A lieutenant general in Romania's security police has defected to the West and is seeking political asylum in the United States, according to reports here and in West Germany.

The West German daily Die Welt said yesterday that the official, Ion Pacepa, vanished 12 days ago while on a visit to Cologne. Informed sources in Washington said the newspaper's account was essentially accurate, but declined to confirm the paper's report that Pacepa is being interrogated by agents of the U.S. Central Intelligence Agency.

Pacepa was apparently a very senior figure in the Romanian security [WORD ILLEGIBLE] - the local equivalent of the Soviet Union's KGB. Sources here said the general was deeply involved in such sensitive matters as the personal safety and travels of Romania's President Nicolae Ceausescu.

One U.S. source recalled that Pacepa was in the United States accompanying Ceausescu on the Romanian's most recent visit last spring.

According to Die Welt, pacepa was last reported leaving his hotel the evening of July 28. He was in Cologne negotiating with the West German firm VFW Fokker for the right to build a German designed passenger plane under license, the paper said. His disappearance was noted by the Romanian Embassy in Bonn which sought help from German police in finding him.

The Welt said pacepa had been in contact with the CIA for some time before his disappearance. Officials here would not confirm that to be the case.

The defection of Pacepa, assuming that he is cooperating with the CIA is a [WORD ILLEGIBLE] not only to the Romanians but also to the Soviets with whom they maintain close touch on security issues.

The Romanian version of the KGB is [WORD ILLEGIBLE] of the most elaborate in the Soviet bloc. Pacepa, Die Welt said, ranked as a vice minister of the organization, in addition to his rank as general - another indication that he had access to important Warsaw Pact secrets.

Informed sources in Washington said that Ceausescu had always been especially careful about his internal security operation and that Pacepa's defection would likely have reverberations in Bucharest.

While Die Welt described Pacepa as one of the "most important" officials in Bucharest, this is considered an overstatement by knowledgeable sources here. Nonetheless, they said, Pacepa played a major role in preparations for high-level talks between Ceausescu and other international leaders, an important function in a country which prides itself on having a role in world affairs beyond its size.

Ceausescu is presently preparing for a visit from Chinese leader Hua Kuo-feng, the first trip by a Chinese party leader to anywhere in Europe outside the Soviet Union.

Pacepa is undoubtedly one of the highest ranking security officials to defect from a Warsaw Pact country in recent years.

Probably the most spectactular recent defection, however, was that of Arkady Shevcenko, the highest ranking Soviet official in the United Nations secretariat who refused to return home in April and received asylum in the U.S.