The West German parliament, called back from summer recess into emergency session, voted unanimously yesterday to strip immunity from a prominent member suspected of involvement in a spy ring.

Minutes after the vote, police searched the office of Uwe Holtz, 34, one of the fastest-rising politicians in the ruling Social Democratic Party and chairman of the Bundestag Committee for Economic Cooperation.

The investigation - apparantly based on information given the U.S. Central Intelligence Agency by a high-ranking Romanian defector - is fast becoming the biggest political sensation in Bonn since Chancellor Willy Brandt resigned upon discovering his aide was a spy four years ago.

Holtz, who voted for the resolution lifting his own immunity, denounced reports of his involvement in a spy ring as "evil suspicions," and insisted that he had "done nothing at all that could justify the suspicion of espionage or any illegal action."

Government spokesman Armin Gruenewald told reporters that the investigation of Holtz was based on information relayed by U.S. intelligence agencies.

The CIA has for the past month been questioning Romanian Lt. Gen. lon Pacepa, a top security official, who disappeared from his Cologne hotel while on a trade mission in West Germany in July.

Pacepa, who was said to be a close friend of Romanian President Nicolai Ceaucescu, reportedly was flown to Washington for interrogation, where he told the CIA of a major spy ring operating close to the heart of the German government.

Meanwhile, informed sources said 12 senior Romanian army and security officers have been arrested in Bucharest in the last two weeks in a purge of Romania's security services, according to Reuter news agency.

[The sources said the Romanian security service was in a state of upheaval following Pacepa's defection. They said several generals, including the director of the state passport and visia office, were among those arrested.]

Holtz, a historian who has been a member of the West German parliament since 1972, was not named during yesterday's brief Parliament session. But shortly after the vote, a public prosecutor and police moved into his office.

Holtz said he had not entered his office since being told of the allegations against him. "I don't want to hide anything," he said.

Parliamentary President Karl Carstens told members that lifting a deputy's immunity involves no assessment of allegations made against a member, but simply permits a police search of a deputy's office.

The first suspect mentioned in the West German press following the disclosure of Pacepa's allegations of a spy ring was Joachim Broudre-Groeger, an aide to Egon Bahr, secretary-general of the Social Democratic Party.

Bahr promised to cooperate fully with investigators, but backed his assistant and said he "remains in his job, of course."

Two leading Social Democrat officials, Brandt and Defense Minister Georg Leber, have been toppled by espionage scandals in recent years.

In 1974, Brandt resigned after his right-hand man, Guenther Guillaume, was unmasked as an East German agent. Leber resigned in February after a secretary in his ministry was accused of handing over hundreds of topsecret documents to the communists.