The Soviet Union has suspended its troop withdrawal from Afghanistan because of heavy attacks by rebels, and a top Foreign Ministry official hinted Friday the pullout might not be completed by a Feb. 15 deadline.

Heavy attacks by insurgents with arms supplied by the United States, Pakistan and other countries "does not provide conditions" for the pullout, First Deputy Foreign Minister Alexander Bessmertnykh told a news conference Friday.Bessmertnykh also said the Soviet Union "is now delivering to the military forces of Afghanistan additional and more powerful means of destruction." Reports have said MiG-27 fighter planes and SS-1 Scud missiles have been introduced by the Soviet Union in Afghanistan in recent weeks and used in attacks on the Afghan resistance.

In Washington, White House spokesman Marlin Fitzwater said the Soviet actions "can only increase tensions in the region and raise speculation that they are't going to live up to the Geneva accords," which call for Soviet troops to be out of Afghanistan by Feb. 15.

The Soviet Union says supplies of arms to the rebels violate the April 14 Geneva agreement under which the Soviet Union agreed to withdraw its more than 100,000 soldiers. It has pulled out half the troops.

"The Soviet Union intends to stand by its obligations under the Geneva accords," he said. But in order for the Geneva agreement to be fulfilled, all four countries that signed it - the United States, Soviet Union, Afghanistan and Pakistan - must obey its provisions, he said.

He said that although the Soviet Union was introducing more powerful weapons in Afghanistan, the quantities of soldiers and weapons remained constant.

Repeating an earlier warning, State Department spokesman Charles E. Redman said, "If the introduction of this weaponry is an attempt to intimidate Pakistan, then Moscow should know that Pakistan enjoys our full support."