KARACHI, PAKISTAN, June 6.-The United States and Britain are withdrawing senior diplomats from Dacca, capital of strife-torn East Pakistan, foreign diplomatic sources said here today.

American Consul General Archer K. Blood leaves for Washington Thursday and will not return, they said. Britain's deputy high commissioner, Frank Sargent will leave for London a week later they said. Neither has completed a normal tour of duty.

American sources explained that Blood went to Dacca on direct transfer from Athens and the time spent in both posts totaled an average assignment.

British sources would make no comment on the move of Sargent, who took up his post in Dacca late last year. Observers here recalled that Blood was thrown into controversy following the Pakistan army's March 25 crackdown of the eastern provinces breakaway efforts.

URGES EVACUATION

On March 30 Blood urged Washington to evacuate ail American women and children in East Pakistan and some men. There were fears for the safety of Americans in what was described privately by U.S. officials "as a massacre"

In related developments elsewhere Reuter reported: In Lucknow, India, Indian Prime Minister Indira Gandhi described the bloodshed in East Pakistan "as the most unabashed example of the use of governmental violence in human history."

"The international community has a duty to impress upon the rulers of Pakistan that democratic urges cannot be suppressed through armed might," she said.

NOT JUST INTERNAL

Mrs. Gandhi made her statement in a message to a national convention of minorities being held in this northern Indian city.

Mrs. Gandhi said: "When 4 million people are forced to flee from their homes and their country into our territory though terror, obviously the matter cannot remain an internal matter of Pakistan."

Meanwhile Indian Foreign Minister Swaran Singh arrived in Moscow the first stop on his six-nation tour to tell the world that India cannot cope with the influx of East Pakistanis fleeing across its borders.

He is due in Bonn on Wednesday; Paris, Thursday; Ottawa, Sunday; Washington, June 15 and London June 18. Estimates of the cholera death toll in eastern India ranged from a conservative 4,000, according to West Bengal State officials, to as high as 10,000, according to unofficial sources in close touch with the relief work, AP reported.]