The parliament of the Baltic republic of Lithuania challenged Moscow's authority Friday by debating a law declaring Lithuanian the official language. A Russian newspaper accused neighboring Estonia of fostering ethnic tension with a similar effort.

The meeting in Lithuania, and demonstrations planned Thursday marking the 70th anniversary of independence in the third Baltic republic, Latvia, were signs of resurging nationalism in the small Soviet republics that are using Soviet President Mikhail S. Gorbachev's reforms to push for greater autonomy.The republics of Lithuania, Estonia and Latvia were independent between the world wars but were annexed by the Soviet Union in 1940 following a pact between the Soviets and the Nazis.

Residents of the Baltics have increasingly pushed for more economic and cultural freedom under Gor-bachev's reform policy. Thousands in the three republics have joined People's Front organizations, which recently have spread to the Slavic republics of Byelorussia and the Ukraine.

The Baltics have been angered by amendments to the national constitution proposed by Gorbachev, saying they would shift the little power they have to central authorities in Moscow and eliminate their constitutional right to secede.

The Supreme Soviet of Lithuania opened a session that was expected to last late into the night with the national language debate, said Vitau-tus Makauskas, an editor with official television, which was providing a live broadcast.

Makauskas said in a telephone interview from Vilnius, the Lithuanian capital, that the language debate would likely be followed by discussions about re-establishing the flag, hymn, and seal of the independent republic that existed before Lithuania was absorbed into the Soviet Union.

Activists said hundreds of people gathered outside the Supreme Soviet on Thursday with flags and banners supporting greater local control.

The United States backed the Baltic nationalists Thursday. State Department spokesman Charles Red-man said in Washington: "The United States does not recognize the forcible incorporation of the Baltic states. The people of the Baltic states have been denied their basic human rights."

Sovietskaya Rossiya, the official newspaper of the Russian republic, Friday cited rising tensions between nationalities in Estonia, picking up a theme sounded by Politburo member and former KGB secret police chief Viktor M. Chebrikov in a visit to Estonia last weekend.