From Peter Hazelhurst Karachi, March 21

Mr. Z. A. Bhutto, the leader of West Pakistan, met President Yahya Khan in the East Pakistan capital of Dacca tonight for crucial talks on the constitutional crisis which has brought the country's two wings to the verge of separation.

Earlier today, the President had talks in Dacca with Shaikh Mujibur Rahman. the East Pakistan leader. He told journalists that he had called on President Yahya merely to seek some "clarification". He would see the President again tomorrow, he said.

Before leaving Karachi today to fly to Dacca, Mr. Bhutto told journalists at the airport that he had agreed to travel to East, Pakistan after receiving "a certain clarification" from the President on Saturday night.

He had earlier told his supporters that he did not know whether he would meet Shaikh Mujibur and the President individually or in tripartite talks.

With the ban on Pakistan flights over India still in force Mr. Bhutto was forced to make a six-hour detour around the tip of India and via Ceylon to Dacca. He was accompanied by 12 senior delegates of his People's Party.

After Mr. Bhutto's aircraft had touched down at Dacca today, two bodyguards armed with automatic weapons escorted the West Pakistan leader along the tarmac. They kept him away from hundreds of journalists who were waiting to speak to him.

As he was driven through the tense streets of Dacca to his hotel, several vehicles filled with soldiers training Sten guns on the crowds of angry Bengalis lining the streets provided a security cover.

Later, hundreds of Bengali demonstrators thronged around Mr. Bhutto's hotel shouting: "You are not our guest. Go back, Bhutto."

The President's success in bringing the two rival Pakistan leaders together in Dacca was a tremendous coup, but several fundamental deadlocks stjll have to be broken.

One such issue concerns the Legal Framework Order which gives the President the right to reject or ratify the constitution.

Another controversy surrounds the make-up of an interim government.