Despite stepped-up military operations that have forced the stationing of 105,000 Soviet troops in Afghanistan, the Soviet Union failed during 1982 to crush Afghan resistance fighters and faces indefinite stalemate in the war there, a senior State Department official said yesterday.

Lawrence A. Eagleburger, undersecretary of state for political affairs, gave that assessment at a press briefing to review the situation in Afghanistan on the eve of the third anniversary of the Soviet Union's invasion of that southwest Asian country during the last week of December, 1979.

These briefings have become an annual event at the State Department. Eagleburger, who recently visited Pakistan to review the situation in neighboring Afghanistan, acknowledged that part of the purpose is to keep world attention focused on U.S. efforts to bring an end to the Soviet occupation.

However, while he praised "the incredible spirit, courage and tenacity" of Afghan resistance forces and repeated U.S. charges that the Soviets are employing chemical warfare against them, Eagleburger's review contained no new information.

According to U.S. estimates, he said, the Soviets have about 105,000 troops in Afghanistan and another 30,000 in a rear-guard capacity on the Soviet side of the border.

Still, he said, this enormous force has been unable to change a situation in which the Soviets and the puppet regime of Babrak Karmal command cities and major highways but cannot control the countryside.

Despite Moscow's failure to achieve its political and military objectives, he continued, there is no sign that the Soviet leadership intends to pursue a negotiated settlement of the conflict.

Eagleburger acknowledged that there were some inconclusive hints of greater Soviet flexibility following the death of President Leonid I. Brezhnev. But, he added, more recent Soviet statements have given "no meaningful indications" of a move toward negotiations, and some signals, such as a recent Pravda article hinting at "hot pursuit" of resistance forces into Pakistan, seem to point at a hardening of the Soviet position.

He reiterated that the United States, which views the occupation as a serious threat to the Persian Gulf region, wants to see a negotiated settlement that would provide for a complete Soviet withdrawal, guarantees of Afghan independence and nonalignment and the return to their homeland of almost 3 million Afghan refugees now in Pakistan.

Since 1980, the United States is believed to have been working through other countries to provide some arms assistance to the resistance groups.

Despite repeated questions about this covert assistance, Eagleburger refused to comment except to say that the resistance fighters appear to be obtaining all of the arms they need by capturing them from the Soviets or working with Afghan army sympathizers.