KARACHI, Pakistan, Feb. 15 — Two major political leaders —one from West Pakistan, the other from the East — clashed today on the constitution that the forthcoming National Assembly has been called to write.

At issue is the East Pakistanis' call for full regional autonomy for their part of the country, which is separated from West Pakistan by more than a thousand miles of Indian territory.

Zulfikar Ali Bhutto, the former Foreign Minister whose left‐wing Pakistan People's party has 86 seats, all from West Pakistan, in the 313 ‐ member Assembly, threatened today to boycott the Assembly sessions. These are scheduled to open in Dacca, East Pakistan, March 3.

Mr. Bhutto said his party would not attend unless it had an assurance in advance that there was “room for compromise or adjustment” in the pro gram of Sheik Mujibur Rahman's Awami League. The league has 167 Assembly seats, all from East Pakistan.

Even as Mr. Bhutto spoke at Peshawar, West Pakistan, the Sheik declared In Dacca that no one would be able to make the Awami League accept any thing other than a constitution based on his program “even at the point of guns.” He said his party was preparing a draft.