DACCA, Pakistan, March 22 —President Agha Mohammad Yahya Khan of Pakistan today postponed the National Assembly for a second time, saying that more delay is needed to resolve the crisis over East Pakistan's demands for self rule.

This announcement and other events today indicated that while the negotiations here are continuing to make progress, it also seemed possible that they could drag on for some time before an agreement was reached.

The President's first postponement of the Assembly was the act that had set off the crisis between the two sections of the country, separated by 1,000 miles of Indian territory.

The Assembly was scheduled to convene Thursday. Its first postponement, on March 1, had caused demonstrations in Dacca. Scores were killed by West Pakistani troops stationed here.

Sheik Mujibur Rahman, leader of the Awami League, the party that has in effect ruled East Pakistan independent of the central Government since last Monday, met again today with President Yahya at President's House here. It was their sixth known meeting since the President arrived from the West two weeks ago. For the first time, they were joined by Zulfikar All Bhutto, Shiek Mujib's archrival and chairman of West Pakistan's leading movement, the Pakistan People's party.

Mr. Bhutto said he was now examining the “general agreement” that Sheik Mujib and the President had reached before he arrived. He said they were all “thinking in terms of one Pakistan,” and that they were discussing both interim and permanent arrangements for the Government.

Mr. Bhutto flew to Dacca yesterday afternoon after several days of unexplained hesitation. He was greeted by hostile Bengali crowds who cursed at him and screamed slogans such as: “We want Bhutto's blood!” The demonstrations continued today but there was no violence.

Many Bengalis in East Pakis tan blame Mr. Bhutto for the present trouble, for he reportedly along with hard‐line West Pakistani generals and business interests who do not want to lose their hold on the East, put pressure on the President to postpone the Assembly, the first time.

Mujib Sees Progress

Sheik Mujib, holding a brief news conference on his lawn after today's 70‐minute talks, said again that progress was being made. Asked the reason for the second postponement of the Assembly, he said, “we can not sit in the National Assembly until and unless they accept our demands. And accordingly Mr. President has postponed it.”

Since the killings, in the protests in early March by the army, Sheik Mujib and his party have seized effective control of the province, calling it Bangla Desh, the Bengal nation. Obeying Sheik Mujib's directives, the Bengalis have boycotted the martial‐law ad ministration here and refused to work in central Government offices. Sheik Mujib's latest demands are that martial law be lifted, all troops be withdrawn to barracks and power be transferred to the people's representatives, namely the Awami League.

Earlier long‐standing demands, on which Sheik Mujib campaigned and won overwhelmingly in the elections in December, are known as the six‐point program. Under it, the provinces, such as East Pakistan, would be granted broad control over their own affairs. The central Government would be a weak one, with powers limited primarily to defense and some foreign policy matters.

Most knowledgeable observers doubt that a final detailed solution will emerge from the current talks. The consensus is that martial law may be softened and some interim govern mental arrangement established until the National Assembly meets, if it ever meets to draft a new constitutional structure. A new constitution would re turn the country to civilian rule. Pakistan has been under military rule for the last two years.

A new structure, It is expected, would provide some form of autonomy for the provinces, Sheik Mujib has told confidants that he will get more than the six points.

It is likely that to protect himself Sheik Mujib will insist that Mr. Bhutto and the President agree on the basic content of the new constitution before he will accept an interim accord.

The feeling is widespread here, however, that the agreement will be a temporary solution, and that it will not be long before East Pakistan will demand complete Independence.

One thing seems clear now in this tense and fluid situation— the army, a West Pakistani instrument, has apparently decided not to try to use violence to find a solution.