KARACHI, Pakistan, Oct. 12 — President Agha Mohammad Yahya Khan said tonight that a National Assembly would be convened Dec. 27, following by-elections to fill the seats vacated after the army moved to crush the East Pakistani autonomy movement, and that he would cede power to a new central government soon afterward.

Gen. Yahya, broadcasting to the nation on television and radio, said that by‐elections would he completed by Etc. 23.

A National Assembly of 313 seats was elected last Dec. 7 in Pakistan's first free election, since independence in 1947. But the Assembly was never convened, and the upheavals and bloodshed in East Pakistan that began in March virtually emptied the seats allocated to the east wing of the country.

The East Pakistani seats represent a majority in the National Assembly, as East Pakistan's population is greater than that of the west.

Government Vacated 78 Seats

Of 169 seats for the east, 167 were won last December by the Awami League, a Bengali nationalist party headed by Sheik Mujibur Rahman.

Since the army crack‐down against the Bengali separatist movement began last March 25, the Awami League has been banned and Sheik Mujib imprisoned. The Government vacated 78 seats in the Assembly on the ground that the elected members had committed crimes against the state.

In fact, only a handful of the remaining Assembly men not disqualified from their seats are expected to come forward. Many have fled to India.

President Yahya said a new central government would be formed “soon after the inaugural session of the National Assembly,” presumably in January. He did not describe the form the new government would take or how it would be chosen. But he said that the National Assembly would have the right within a period of 80 days after transfer of power to a new central government to propose amendments to a constitution now being prepared under General Yahya's direction.

The President, who is leaving this week to participate in Iran's observances of 2,500 years of monarchy, also warned of an Indian war threat. While there is no cause for alarm, he said, “it is obvious that there is a serious possibility of aggression by India against Pakistan.”

He also charged that “India has moved forward army formations of all types including infantry, armor and artillery, all around the borders of East Pakistan” and asked that the international community “impress upon India the need to desist from interfering in our internal affairs and to withdraw her forces from our borders.”