EAST BERLIN, DEC. 11 -- Soviet leader Mikhail Gorbachev briefed Warsaw Pact leaders on the U.S.-Soviet summit meeting here today in a short session marked by the absence of Romanian President Nicolae Ceausescu.

Arriving here late this morning after a direct flight from Washington, Gorbachev met for about two hours with the Communist leaders of East Germany, Poland, Hungary, Czechoslovakia and Bulgaria. He joined them for lunch before leaving this afternoon for Moscow, where he arrived tonight and was welcomed by the Soviet Politburo and U.S. and British diplomats in a televised ceremony.

Following the brief meeting, the pact leaders issued a statement expressing "full support and high appreciation" of the results of the summit and the "great effort" of Gorbachev. The U.S.-Soviet treaty on intermediate-range nuclear missiles, the statement said, was "proof of the vitality of the new way of thinking" Gorbachev has introduced to East Bloc strategic policy.

The meeting and its routine concluding statement were colored by the absence of Ceausescu, who has played a maverick role in the Warsaw Pact for years and recently faced a violent rebellion at home by provincial workers unhappy with extreme domestic austerity.

Romania was represented here by its foreign and defense ministers, the other members of the three-member delegation that each state normally sends to such Warsaw Pact sessions.

East German Foreign Ministry spokesman Wolfgang Meyer said the 69-year-old Ceausescu, the ruler of Romania since 1965, could not attend because he was busy with preparations for a conference of the Romanian Communist Party scheduled to begin on Monday.

However, East German officials privately expressed displeasure at Ceausescu's absence and suggested that he may be struggling to sustain his hold over the Romanian party in the wake of riots Nov. 15 in the city of Brasov.

Western observers here suggested that Ceausescu's absence might also reflect growing tension between him and Gorbachev, whose efforts to reform East Bloc socialism are antithetical to Ceausescu's personality cult and neo-Stalinist regime.

Ceausescu in the past has marked Romania's differentiation from the rest of the Warsaw Pact with acts ranging from refusing to participate in the 1968 invasion of Czechoslovakia to breaking the Soviet-led boycott of the Los Angeles Olympics.

Western diplomats in Bucharest said the Romanian press gave little coverage to the Washington summit, in marked contrast to other East European states. When the U.S.-Soviet arms treaty was signed Tuesday, Romanian television did not mention it and only a brief story appeared the next day on the back page of the party newspaper Scinteia.

In their statement, the pact ministers expressed optimism that U.S.-Soviet negotiations would lead to new arms agreements. A 50 percent cut in strategic weapons, it said, "would be possible within the forseeable future," while accords on the destruction of chemical weapons, banning of nuclear tests and reduction of conventional military forces in Europe were also within reach.