The Soviet press, for the first time since Moscow's military intervention in Afghanistan two months ago, yesterday issued major reports of widespread unrest there and blamed foreign-backed "counter-revolutionaries."

In its report from Kabul, Pravda said, "Today Kabul has not yet returned to normal life. It is felt, however, that the peak of the insurgency has passed." Pravda added that "the army and militia are fully in control of the situation."

Clashes between opponents of the Soviet-installed Marxist government in Afghanistan and Afghan and Soviet forces have caused hundreds of casualties in Kabul and other cities in recent days, according to reliable but sketchy reports.

Journalists trying to fly to Kabul from Pakistan were barred from boarding the plane yesterday at the request, Pakistan airline officials said, of the Afghan government.

Meanwhile the Afghan government launched a vigorous campaign to persuade the public that Soviet troops were in Afghanistan because of a serious threat to that country's national security and would leave whenever the Afghan government asked them to.

A Soviet radio station added a new element to that campaign by charging yesterday that U.S. ambassador Adolph Dubs, killed in Kabul a year ago, was murdered by the Central Intelligence Agency as part of a plot to destabilize the Afghan government.

Dubs was killed when Afghan troops stormed a hotel room where he was being held hostage by unidentified Afghan gunmen. U.S. officials had pleaded with Afghan authorities and their Soviet advisers to refrain from such action.

Prava's account quoted Abdurrashid Aryan, the Afghan justice minister, as saying it was clear from violent demonstrations Friday that Kabul had been infiltrated with trained agents from abroad.

Their task, Aryan said, had been to stir up unrest and religious strife, sabotage decisions of the government, wreck the economy and hinder Afghanistan's Marxist revolution.

The unusually detailed account of unrest contrasted with previous Soviet press coverage of Afghanistan, which has reported only sporadic violence and suggested that the new Marxist government of Babrak Karmal was winning increasing popular support.

Afghan sources in New Delhi said they received reports from Kabul yesterday that Soviet troops had blocked access to bridges over the river that dissects the city, splitting the Afghan capital in two in an apparent attempt to protect the Soviet Embassy and a Soviet housing area from demonstrators.

Meanwhile, reports circulated in India and Pakistan that two of Babrak Karmal's closest advisers, Vice President Sultan Ali Kishtmand and Mahmud Bariyari, have died in Soviet hospitals of wounds suffered in an unexplained gun battle in the capital Feb. 7.

The Afghan Embassy in Moscow denied the reports as "nonsense and absolute propaganda."