Rebels in Afghanistan said yesterday that they killed President Mohammed Daoud and his brother because they "madly" resisted Thursday's coup.

According to reports from foreign diplomats in the Afghan capital, Kabul, there was continued fighting yesterday between rebel forces and air force units that had backed Daoud, but not on the level of the intial clashes Thursday.

A broadcast by the rebels claimed "complete control" of Afghanistan. Several diplomats, however, questioned whether the rebels' control actually extended to the important military centers of Kandhar and Harat.

"To seize Kabul is not to seize Afghanistan. Resistance in the form of guerrilla warfare could continue for months," one diplomat commented.

A rebel broadcast said that the new Military Revolutionary Council had ordered all top civilian and military figures in the Daoud government to report to the Defense Ministry. Reports reaching the outside world said that Interior Minister Kadir Nuristani had been arrested.

The Council also announced the abolition of the constitution, only recently introduced by Daoud, and said Afghanistan would be ruled by military decree.

Broadcasts of the Council, which is headed by Air Force Col. Dagawar Abdul Khadir, repeatedly stressed that the new government's foreign policy was based on "strict nonalignment, peaceful coexistence and the tenets of Islam."

Western diplomatic sources Thursday said that the coup leaders could be characterized as "pro-Soviet."

The rebel account of the death of Daoud and his brother, Naim, a close poliitical advisor, did not make clear whether they died in fighting for the presidential palace or were executed after being taken captive.

Diplomatic sources in Paris said that other members of Dauod's family had taken refuge in the French Embassy.

The country's airports and borders remained closed and all commercial communication channels were cut.Western diplomats in Kabul, however, were providing information to their capitals via their embassy radio and telex facilities.

In their account of yesterday's combat, they said Soviet-built Su7 fighters of the Afghan Air Force fired rockets down Darulaman Road in the center of the city toward the Justice Ministry and the headquarters of the army's Central Corps. They said the planes ran into heavy antiaircraft and one plane was shot down.

A heavy pall of smoke hung over the city, and no civilians were seen out of doors despite rebel radio exhortations to carry on "as normal." Rebel troops surrounded some Western embassies and refused to allow diplomats to leave their compounds.

The radio made frequent attacks on the Daoud government, charging that the ousted president was the "worst tyrant, whose regime was characterized by corruption and looting." It claimed that Daoud had handed over the wealth of the nation to his family and foreign interests, which were not identified.

The revolt followed 10 days of political unrest stemming from the murder of a Communist leader whose funeral turned into an antigovernment demonstration. Seven Communists were arrested after outbreak.