The State Department has acknowledged that the central government of Pakistan has used U.S.-supplied tanks and jets in putting down the rebellion by breakaway East Pakistan.

But it said that Pakistan was under no obligation to consult with the United States on the transfer of the equipment from one part of the country to the other.

The action by Pakistan's central government was taken despite secret diplomatic pressure from the United States, according to the department.

The statements were made by David M. Abshire, assistant secretary of state for congressional relations, to four senators who had asked for information on the status of U.S. military and economic aid to Pakistan.

The letter from Abshire was addressed to Sens. Walter Mondale (D-Minn.), Edmund S. Muskie (D-Maine), Edward W. Brooke (R-Mass.) and Mark 0. Hatfield (R-Ore.).