NEW DELHI, India, Friday, Aug. 15—The armed forces of Bangladesh mounted a coup before dawn today, ousting the President, Shiek Mujibur Rahman, from the helm of the country he led to independence four years ago, Western diplomatic sources reported.

The sources said the military struck at 5:15 A.M. (7:15 P.M. Thursday, New York time) by arresting Sheik Mujib and then Installing a former close associate, Khondar Kar Moshtaque Ahmed, as the new President.

Bangladesh, former East Pakistan, came into being as result of months of civil conflict that led to war in December, 1971, between India and Pakistan.

According to diplomatic reports reaching New Delhi, there was sporadic fighting around Dacca, the capital, at the start of the coup. The reports said that two hours later, “by and large everything is quiet.”

The initial fragmentary reports indicated the coup might have been arranged by pro-Western political and military forces. Mr. Ahmed was considered a member of a lobby critical of Sheik Mujib's attempts to steer Bangladesh close to India and the Soviet Union.

Mr. Ahmed served as foreign minister of the provisional Bangladesh revolutionary government during the 1971 civil war that led to independence.

After independence, he was moved to lesser Cabinet posts following accusations that when he served as foreign minister during the civil war he had participated in American‐initiated diplomatic attempts to prevent the break‐up of Pakistan, then the world's most populous Moslem nation.

Americans Safe

Special to The New York Times

WASHINGTON, Aug. 14—The State Department said tonight that it had received word from the United States Embassy in Dacca that a coup d'etat had taken place in Bangladesh.

No further information was immediately available from the embassy, the spokesman said.

The spokesman said that there was “no danger to American lives or property” in the reported coup.

Mujib Arrest Reported

WASHINGTON, Aug. 14 (AP) —A State Department source said reports from the U.S. Embassy indicated that Sheik Mujib was under house arrest.