The Soviet ambassador to Afghanistan, stepping up pressure on Afghan rebels to halt their advances, said Saturday the agreement on Soviet withdrawal is near ruin because of U.S. and Pakistani arms supplies to the insurgents.

The statement to legislators in the Afghan capital, Kabul, followed an announcement Friday that the Soviet Union had stopped removing its soldiers from Afghanistan because of increased attacks by Islamic guerrillas.Soviet SS-1 missiles and sophisticated MiG-27 warplanes also have been sighted in Afghanistan in the past week.

The concerted diplomatic and military pressure indicated the guerrilla offensive against the pro-Soviet Afghan government has pushed the Soviet Union past its level of tolerance.

The Soviet news agency Tass quoted Ambassador Yuli Vorontsov as saying the supply of weapons to guerrillas by the United States and Pakistan "is a very serious blow to the Geneva accords which practically torpedoes them."

Vorontsov, appointed ambassador last month, also is a first deputy foreign minister with considerable influence and experience negotiating the Red Army's exit from Afghanistan.

In a separate dispatch, Tass said 450 guerrillas were killed and 160 wounded in fighting in nine Afghan provinces last week. It said 49 surface-to-surface missiles and two missile launchers were captured. The dispatch could not be independently confirmed.

Elsewhere, the pilots of the state-run Indian Airlines have refused to fly to the Afghan capital, claiming unsafe conditions at the airport. The move forced officials to cancel trips to Kabul, an airlines spokesman said Saturday.

Pilots recently have witnessed a marked deterioration in the security conditions around and inside the Kabul airport, said A.K. Sivanandan, an airlines official. Indian Airlines operates two Boeing 737 flights a week to Kabul, and its pilots have in the past complained to their management of poor safety conditions at the Kabul airport.

Vorontsov's comments came during a meeting of the foreign affairs commissions of the two houses of the Afghan Parliament.

"The time has come for a new international debate of all aspects of the situation in Afghanistan and around it, because foreign powers _ Pakistan and the United States _ are involved here that push the opposition toward continuing the blood-letting," he said.

Vorontsov said U.N. Secretary-General Javier Perez de Cuellar could play an important role in any new debate on Afghanistan.

Perez de Cuellar, in Geneva on Saturday for Iran-Iraq peace talks, did not comment on the Afghanistan developments during brief remarks to reporters.