The government declared a nationwide state of emergency Saturday and blamed U.S. aid to Afghan guerrillas in part for the move, which sharply curbs civil liberties.

The emergency was announced on state-run radio and television by President Najib, who said it was needed "to ensure peace and security" in Afghanistan. It came three days after the last Soviet soldiers, who had been backing Najib's army in its war with Moslem guerrillas, left the country.During the day, troops, tanks and armored personnel carriers appeared at most intersections in Kabul, and soldiers were stationed on the roofs of buildings.

Foreign Ministry spokesman Mohammad Nabi Amani told foreign journalists that troops had the right to open fire if they believed reporters or photographers were behaving suspiciously.

The city of 2.25 million people remained relatively calm. But guerrillas surround Kabul, and many diplomats believe the government will collapse shortly.

In Islamabad, Pakistan, Afghan guerrilla leaders nominated Mohammad Nabi Mohammadi as acting president and Ahmad Shah as acting prime minister of an interim government that would take over if Najib's government fell. Sibghatullah Mojaddidi, one of the guerrilla party leaders, stepped down as acting head of the alliance to allow Mohammadi to be Supreme Council head in addition to interim president, officials said. A special council of 400 delegates was to formally approve the appointments Sunday.

The state of emergency allows the government to suspend or limit constitutional rights that protect against confiscation of property and searches of property; provide for confidentiality of correspondence and telephone conversations; allow peaceful assembly and demonstrations; protect freedom of expression; and provide for freedom from compulsory labor.

Najib said the emergency was "temporary," but he did not set a time limit. Under the constitution, an emergency can last three months but can be extended with the consent of the National Assembly.

Amani said clandestine activities that were terrorizing the Afghan people prompted the declaration. Speaking at a news briefing, he said these activities included the circulation of "night letters" - unsigned pamphlets warning residents to stay off the streets, close their businesses and stay away from the airport.

Amani also said the refusal of the United States and Pakistan to halt the supply of arms to the rebels made the state of emergency necessary.

"Islamabad, Washington and certain other circles are conspiring to disrupt the political and economic stability and are endangering peace and trying to stop the realization of the policy of national reconciliation by demanding the continuation of war and bloodshed," he said. "This is a serious threat to the sovereignty and territorial integrity of Afghanistan."