Soviet authorities have reinstated Georgian as the official language of Soviet Georgia after demonstrations there last week over a proposed new constitution that had eliminated the language as the republic's official tongue.

The demonstrations occurred Friday in the Georgian capital of Tbilisi, when several hundred university students, some of their professors and others apparently marched from the campus about a mile through downtown to the steps of the government buildings where the Georgian parliament was meeting to adopt the new constitution.

The abrupt reversal is one of the clearest indications in recent years of the volatility of the question of the nationalities in the Soviet Union, where Great Russians preside over a vast land embracing more than 100 different languages and dozens of peoples, each with clear and distinct social, cultural and ethnic differences. The language change in Georgia shows again how delicate the question is to the leadership.

Georgia, birthplace of Josef Stalin, has always seethed with nationalist tendencies and resentment against Russians. Even today, 22 years after their Soviet leader Nikita Khrushchev denounced Stalin, the dictator's portrait is common throughout the republic.

The new local constitution is modeled after the new national law adopted by the Supreme Soviet last year. It was a pet project of Leonid Brezhnev, Soviet president and Communist Party chief.

The troubles in Georgia are sure to be an embarrassment for Brezhnev and for the ruling Politburo, which pays minute attention to every internal political question.

The new fundamental law, a replacement for a local constitution that had been in force in the former [WORD ILLEGIBLE] caucasian Republic since 1922, sought to replace Georgian as the sole official language of the republic [WORD ILLEGIBLE] wording asserting that all the languages of the polyglot republic were to be considered equal.

The dominant segment of the republic's population, apparently interpreted this change to mean further "Russification" of their republic.

According to the Georgian newspaper Zarya Vostoka, Georgian Communist Party chief Eduard Shevarnadze conceded the reversal in a speech Friday. It is unclear whether he made his speech before the student march or after, but it is the nature of Soviet officialdtm to move slowly and only after substantial deliberation, which indicates that protests over the language change may have been in the air for some time.

Two American lawyers who were in Tbilisi last week said here yesterday they were told by some Georgians that at least a regiment of troops had been moved into the outskirts of the capital. The lawyers, Robert B. McKay and S. Eric Rayman, said they were told the soldiers were equipped with high-pressure water hoses to repel demonstrators, but the equipment was not used. It was impossible to check the reports.

Foreign travelers reported Saturday however, that their flights into Tbilisi had been canceled on Friday and Saturday without explanation.

The lawyers said they were also told that similar demonstrations over language changes had occured in Armenia in the past two weeks.

The Georgian newspaper quoted Shevarnadze as saying that "proceeding from the democratic nature of our society, and the constitution, we have arrived at the conclusion that it is expedient of leave in effect the known formulation of the acting (1922) constitution, which proclaims Georgian the state language."

At the same time, the party chief, who as political head of one of the Soviet Union's 15 national republics is an important power in the republic and the nation, left room for the study and use of Russian. He seemed to go out of his way to mollify possible criticism from Moscow, capital of Great Russia as well as of the nation.

"Again we have to tell our native people and our youth that equal with our esteem for the native language, equal with studying the native language, if we want to aspire to the light, if we want to take possession of sciences and keep in touch with current world civilization, it is necessary to respect and study the wonderful and rich language of the Russian people.!"