MOSCOW, NOV. 18 -- Boris Yeltsin, ousted as chief of the powerful Moscow Communist Party organization a week ago, has been given a government post with responsibilities for construction, the official news agency Tass reported tonight.

Yeltsin, 56, was publicly criticized by Communist Party leader Mikhail Gorbachev and others for challenging the party's authority. Yeltsin's removal from the Moscow job marked Gorbachev's first major political crisis, exposing a split in the top ranks of the party leadership.

Tass reported tonight that Yeltsin will become a first deputy chairman of the U.S.S.R. State Committee of Construction, with ministerial rank. The title of minister will allow him to sit on the Council of Ministers, the top administrative body in the Soviet government.

The new job is a marked demotion for Yeltsin, one of the most fervent supporters of Gorbachev's proposed reforms. As Moscow party chief, Yeltsin was made a candidate member of the ruling Politburo, a title which he is sure to lose when the party's Central Committee meets again.

Yeltsin's signature was missing Monday from the list of officials signing an obituary of a party leader in party newspapers. But the absence was seen here as a sign of Yeltsin's illness, not his loss of the Politburo title, which can be removed only by the full 300-member Central Committee.

A Foreign Ministry spokesman confirmed yesterday that Yeltsin was in the hospital with a heart condition, but denied rumors that he had a heart attack.

His new job will allow Yeltsin to stay in Moscow, saving him from an assignment to the provinces, which in Soviet terms is political exile. It also signals that despite "political mistakes" committed in an outspoken speech against party leaders Oct. 21, Yeltsin does not face expulsion from the party.

But the new position does nothing to soften the political impact of Yeltsin's humiliation, carried out with drama at a meeting Nov. 11 of the Moscow city party committee, chaired by Gorbachev. At the meeting, covered in detail by the Soviet press, several of Yeltsin's former colleagues, many of them demoted by him during his two years in the job, rose to denounce their former boss for offenses ranging from not answering phone calls to stabbing the party "in the back."

Since the meeting, several groups in Moscow have petitioned for more complete information on Yeltsin's ouster, in particular the publication of his Oct. 21 speech. The official press has remained silent, except for a brief item in today's edition of the weekly Moscow News in which Gavril Popov, a leading reform economist, notes critically that Yeltsin tried to establish his "own position" outside the party line.

Yeltsin, a native of Sverdlovsk, an industrial city in the Ural mountains, has a background in construction. In 1985, he was brought to Moscow to work first as chief of the construction department in the Central Committee, then as party secretary in charge of construction. He became first secretary of the Moscow party organization in January 1986, replacing long-time leader Viktor Grishin.

Last week, Viktor Afanasyev, editor of the party newspaper Pravda and a Central Committee member, hinted at Yeltsin's future job when he told a group of visitng American newspaper editors that Yeltsin could always find work in construction.