An official from the U.S. Embassy here is being expelled from the Soviet Union after allegedly being caught "red-handed" in the act of spying, according to the Soviet news agency Tass.

Michael Sellers, a second secretary in the embassy, was detained Monday while holding "a clandestine meeting with a Soviet citizen," who also was involved in spying, Tass reported today.

A U.S. Embassy spokesman confirmed that Sellers had been ordered expelled but declined all further comment.

Tass said that Sellers was charged with conducting "intelligence-gathering activities" incompatible with his diplomatic status and that he has been declared persona non grata.

Tass said the Soviet citizen who met with Sellers had been "recruited by U.S. intelligence" and has been arrested..

The detainment "cut short" an espionage operation by the U.S. secret service, according to Tass.

Sellers, who has lived in Moscow for less than a year with his wife Lucy, is still in the Soviet capital but is unavailable for comment.

Western diplomats in the Soviet capital consider the expulsion of a U.S. official -- the first in nine months -- retaliation for the recent U.S. demand that Moscow reduce its New York-based United Nations staff by 40 percent in the next two years. In calling for the reduction last Friday, the United States said that members of the Soviet staff at the United Nations had been engaged in "wrongful" acts, "including espionage."