The Libyan government of Col. Mummar Qaddafi has been holding two Americans for several weeks, apparently on espionage charges, it was learned yesterday. Meanwhile, 25 other U.S. citizens were expelled on similar charges Monday, State Department officials confirmed.

The State Department said it had information that seven other Americans were about to be expelled. A broadcast by the official Voice of the Arab Homeland said the Americans, mostly oil company employes, were deported for "spying and having connections with terrorist organizations."

It was unclear whether the expulsions were related to the U.S. government's declaring unacceptable six members of the Libyan diplomatic staff here since April 2. The six, who have since returned to Libya, were accused by the State Department of harassing and intimidating Libyan students in the United States.

The United States has had no diplomatic representation in Libya since May 5, when the last two American employes in the Tripoli mission went on what was diplomatically described as an extended "shopping trip" in neighboring Tunisia. Consequently, State Department officials stressed, the approximately 2,500 Americans in Libya are not protected by the American government.

Officials identified the two Americans seized some weeks back as Michael Price and Roger Frey. A Libyan broadcast report said they were being held for spying, but U.S. officials were unable to confirm this. A third American, who could not be identified because of the Privacy Act, has been in jail in Tripoli since July, serving a three-year sentence for a drug offense.

Qualified observers have connected a recent campaign by Qaddafi to eliminate opponents of his rule living in exile to growing internal unrest and an apparent purge inside Libya.

U.S. observers said there have been reliable reports that 1,500 to 2,000 Libyans -- including senior officials -- have been arrested in recent months, mostly on corruption-related charges. There have also been regular show trials on Libyan television.

Other, unconfirmed reports indicate that many opponents of Qaddafi have been executed or "committed suicide." The Neue Zuercher Zeitung newspaper in Zurich reported yesterday that hundreds of Libyans have been executed in the purges, citing various unnamed sources.

The newspaper said the sources reported a rebellion against Qaddafi's people's committees in the city of Tobruk in which 11 persons were killed and 32 injured.

Six Libyan dissidents living in Europe have been slain since mid-March, and another was recently killed in Beirut. In most of the cases, law enforcement officials have taken Libyan nationals into custody and diplomatic sources say they believe the killings are tied to a worldwide campaign of intimidation against Qaddafi's opponents.

Qaddafi recently issued a final warning to dissident exiles to return home "or they will be liquidated wherever they are." Numerous other official Libyan pronouncements since February have called for the "physical liquidation of the enemies of the revolution abroad."

Officials in the United States and Western Europe have expressed concern that Libya's diplomatic missions, newly restyled "people's bureaus," may play a key role in the intimidation campaign, and police in several countries have been on the alert against further acts of violence against anti-Qaddafi Libyans. Britain particularly has been concerned and four Libyan representatives were asked to leave London Monday.

On Monday, Libyan students loyal to Qaddafi peacefully took over their country's embassies in nine countries, adding to the eight "people's bureaus" that already existed.

The United States insists that it wishes to maintain good relations with Libya, which supplies it with 10 percent of its oil imports and 3.5 percent of the total U.S. supply of crude. Relations have been strained, however, since the American Embassy in Tripoli was stormed by a Libyan mob last December.