Mehmet Shehu, 68, prime minister of Albania since 1954 and the heir apparent to rule the tiny Balkan state, died Thursday night in Tirana, Albania.

First reports of Mr. Shehu's death were given in a Radio Tirana news bulletin Friday night. The news bulletin said he had committed suicide. The Albanian ATA news agency issued an official statement Saturday confirming the suicide.

The agency quoted a statement by the central committee of the Albanian Communist Party and government as saying that Mr. Shehu committed suicide Thursday night "at a moment of nervous breakdown." The statement gave no further details about how Mr. Shehu had died.

Mr. Shehu had been considered the almost certain successor to Communist Party leader Enver Hoxha, who has ruled Albania on orthodox Stalinist lines for the past 37 years.

During his time as government chief, Mr. Shehu outlasted years of ruthless infighting within the Albanian leadership to carry the country through abrupt ideological changes. These included shifting Albania from the Soviet Union's orbit into an alliance with China, which has now broken after a 17-year link.

He had been right hand man to Mr. Hoxha for three decades and was reported to have been handling most of the day-to-day running of the country, leaving Mr. Hoxha to develop long-term policy.

Mr. Shehu was educated in France and at Tirana Technical College and fought in the Spanish Civil War.

He was made chief of staff of the Albanian army in 1946 and became a member of the political bureau of the Albanian Party of Labor in 1948.

He held the posts of vice president of the Council of Ministers and interior minister from 1948 to 1954, when he became prime minister. He was also defense minister from 1974 to 1980.

Mr. Shehu was not reported to have had any health problems since a 1972 operation in France for an undisclosed ailment. However, speculation about his health began this year when he gave up the defense minister's post.