Special to the New York Times

NEW DELHI, March 29--In its battle to put down the independence movement in East Pakistan, the Pakistani army has resorted to widespread killings of civilians, according to reports reaching here today from unimpeachable foreign diplomatic sources in Dacca.

These reports were confined to Dacca, a city of 1,500,000 people, and all the reports were confined to events up to Saturday night. The army attack began Thursday night. The following is a verbatime report relayed to New Delhi from these sources:

"The tanti Bazaar and Sankhari Bazaar areas of Dacca inhabited by more than 10,000 people, were surrounded by the army. Houses were set on fire and the people were being butchered. Even residents fleeing the area have not been spared."

Another report from other highly reliable foreign diplomatic source in Dacca said the office of Ittefaq, a Bengali-language daily newspaper, was burned with 40 persons inside.

There have been reports fromt he interior telling of killings of civilians, some later than Saturday, but these reports do not come from diplomatic sources and are impossible to evaluate.

Diplomatic sources in Dacca report they have received what they consider reliable reports from the interior that heavy fighting was going on in some areas between the army and civilian resistance forces, with the army strafing from the air and using tanks and heavy artillery on the ground.

The over-all death toll is not known. The Clandestine Radio of the Resistance Movement said that 300,000 East Pakistanis were killed by West Pakistani troops in the first 48 hours of the army's attack.

Widely conflicting reports about who is winning in East Pakistan continue to flow into New Dehli. Because of a blackout of all the normal news channels and communications from East Pakistan, it is impossible to tell from these unverifiable reports whether the Pakistani Army is in control and the province is relatively calm, as it asserts, or whether the civilian resistance has made teh army's position desperate, as the resistance has said in some of its clandestine broadcasts.

The fighting in East Pakistan began last Thursday night when the Pakistani army, without warning, attacked civilian population centers in an effort to crush the province's non violent movement for autonomy. The army units--all West Pakistani troops--opened fire with artillery, rockets and machine guns.

Since then, a resistance effort has been launched with East Pakistani policement and a militia called teh East Pakistan Rifles fighting the army with the aid of civilians armed with knives, sticks and homemade guns.

The current crisis goes back to a decision by President Agha Mohammad Yahya Khan to postpone the meeting of the National Assembly that was to have begun to draft a constitution ending military rule.

That meeting would have been dominated by East Pakistan's principal party, the Awami League of Sheik Mujibur Rahman, which had won a clear majority in election in December with its demands for regional autonomy.

The decision to postpone the session touched off protest demonstrations, strikes and rioting in East Pakistan, and the army was reported to have killed scores of Bengalis. The Awami League gradually took control of East Pakistan.

Negotiations were thne begun involving the President, Sheik Mujib, Zulfikar Ali Bhutto, the dominant political leader of West Pakistan. Despite public reports of progress as late as last Tuesday, authoritative sources now say that West Pakistani interests had decided from the start not to yeild their hold on East Pakistan.