MOSCOW, JULY 21 -- Afghan leader Najibullah used his first Soviet press conference to argue today that his policy of national reconciliation is progressing well, with rebels returning from abroad and villages gradually coming under broad multiparty rule.

The figures he gave, however, indicated only minor advances. Since the national reconciliation process was announced in January, he said, 67,000 Afghan exiles have returned. Western diplomats have estimated that 4 million Afghans left the country since the Soviet invasion late in 1979.

Najibullah also said that 23 government ministries could go to noncommunist party members as part of the move to build a coalition government, but added that his ruling People's Democratic Party would be dominant in any coalition.

Najibullah's press conference, coupled with recent reports of increased Soviet casualties in Afghanistan, suggested a stalemate there, particularly with regard to the withdrawal of Soviet troops.

A timetable for Soviet withdrawal "can only be decided after the outside interference sponsored by the U.S. and its NATO allies is ended and there are firm guarantees that it will not be resumed," Najibullah said.

In a meeting with Soviet leader Mikhail Gorbachev Monday, Najibullah and the Kremlin chief agreed that the policy of national reconciliation should be continued, the Soviet news agency Tass reported.

Last night, Tass also said the two leaders discussed "additional steps and measures in the interests of the fastest possible normalization of the situation around Afghanistan."