Special to the New York Times

New Delhi, Saturday, March 27 -- Open rebellion broke out in East Pakistan yesterday, with fighting reported in several cities, and a radio station broadcast a proclamation of an independent people's republic.

The proclamation was attributed to Sheik Mujibur Rahman, the East Pakistani Nationalist leader, whose Awami League has been campaigning for autonomy for the eastern wing of Pakistan. He and his chief aids were reportedly driven underground by martial-law authorities sent from West Pakistan, about 1,000 miles away on the other side of India.

Most sources of communication with East Pakistan were broken off, and reports of the rebellion came mainly from Indian news dispatches quoting what they described as authoritative sources in the area. President Agha Mohammad Yahya Kahn, who flew back to West Pakistan late Thursday after the failure of his 11 days of negotiations with Sheik Mujib, said in a broadcast:

"I have ordered the armed forces to do their job and fully restore the authority of the government."

Accusing Sheik Mujib of treason, the President outlawed the Awami League, East Pakistan's dominant political party, which in three weeks of strikes and other protest action had become in effect the regional government. The protest had been against President Yahya Khan's decision to postpone the opening of the National Assembly, which the Awami League dominated. The assembly was to have met March 3 to start drafting a constitution to return Pakistan to civilian rule.

The present rebellion erupted when the Pakistani Army moved to reimpose the authority of the military government, based in West Pakistan, on the East.

Indian News dispatches said the fighting was between troops from West Pakistan on one side and East Pakistani policemen and paramilitary organization known as the East Pakistani Rifles on the other.

The Press Trust of India, this country's main news agency reported that fighting was raging at Chittagong, Comilla and Rangpur, as well as at Dacca. It said that at least 10,000 soldiers from West Pakistan had been transported to the East, raising the total there to about 70,000.

Reports of fighting also came from what one Indian dispatch described as a clandestine radio station, presumably in the northern part of East Pakistan. This, it said, was the same station that announced the proclamation of an independent nation, Bangla Desh whose name is Bengali for the Bengal Nation.

The broadcast said that those battling for East Pakistani independence had surrounded West Pakistani troops in the cities of Sylhet, Jessore, Barisal and Khulna as well as in Chittagong and Comilla.

"Sheik Mujibur Rahman is the only leader of the people of independent Bangla Desh and his commands should be obeyed by all sections of people to save the country from the ruthless dictatorship of West Pakistanis," the broadcast said.

It reiterated the Awami League's decision to organize a strike throughout the eastern wing today to protest the army attacks in the last few days that reportedly had resulted in the death of more than 100 civilians.

Curfew is announced

The first confirmation that the Government in West Pakistan had reasserted control of the East came early yesterday when the Dacca radio went off the air briefly and the army authorities came on to announce a 24-hour curfew in Dacca and seven other districts in East Pakistan. The radio station had been under the control of the Awami League which had seized it during the constitutional crisis.

Yesterday's developments followed an announcement Thursday night of "a serious deadlock" in the talks between President Yahya Khan, Sheik Mujib and Zulfikar Ali Bhutto, chairman of the dominant political party of West Pakistan, the Pakistan People's Party.

President Yahya postponed the March 3 meeting of the National Assembly when Mr. Bhutto said his party holding only a minority of the seats would not attend. Opposing Sheik Mujib's demand for autonomy, Mr. Bhutto favored what he described as an effective central government.

Soon after the breakdown Thursday of the President's talks with Sheik Mujib, the martial-law administrator for East Pakistan, Liut. Gen. Tikka Khan, began issuing a series of stringent orders to assert army control. The army seized the Intercontinental Hotel in Dacca and confined scores of foreign newsmen to the building, prohibiting news dispatches, reports said.