NEW DELHI, April 18—The predominantly East Pakistani staff of Pakistan's diplomatic mission in Calcutta took over the establishment today and transformed it into a mission of the newly proclaimed pro visional government of Bangla Desh—the Bengal Nation.

According to news reports from Calcutta, the head of the mission, M. V. Hossain Ali, hauled down the Pakistani flag and hoisted the Bengali independence movement's green, red and gold standard as the Bengali staff cheered.

It was the first Pakistani diplomatic mission to declare its allegiance to the government of Bangla Desh since the Pakistani Army launched its attack in East Pakistan on March 25 to try to crush the popularly supported movement for autonomy.

The Pakistani mission in Calcutta was a deputy high commission. As members of the British Commonwealth, Pakis tan and India maintain high commissions rather than embassies in each other's countries. Lower‐level missions in cities other than the capital are deputy commissions.

Independence Declared

Mr. Ali, the deputy high commissioner, announced that henceforth the Calcutta deputy high commission “will function as the mission of Bangla Desh in India.” The move came a day after a ceremony inside East Pakistan that officially declared the creation of the new Bengali nation—a formality that was preceded by several similar announcements.

Mr. Ali said that more than 50 of the approximately 80 members of the mission were Bengalis. He said the 30 West Pakistanis would not be kept in the mission and that any of them “who wish to return to We :t Pakistan will be al lowed to do so without hindrance and at the earliest opportunity.”

The Indian Government withheld comment tonight on the Calcutta development. India, while showing strong sympathy to the Bengali cause and denouncing the Pakistani Army's action as “medieval butchery,” is taking pains to maintain a restrained and correct diplomatic posture. New Delhi has refrained so far from recognizing Bangla Desh.

Meanwhile, in East Pakistan, clashes between the Pakistani Army and the Bengali resistance fighters were reported to day in several sectors. Indian press reports indicated that the army was continuing its air and land offensive to extend its control as much as possible before the monsoon rains be come heavy in a few weeks and make troop movements difficult.

The army already controls almost all the major towns and cities and is trying to spread out into the countryside, much of which is in Bengali hands.

Indian press reports from border areas today said that according to fleeing villagers, the army is continuing to kill students and other persons of potential leadership caliber. In the town of Meherpur, the reports said, the army troops lined up 25 college students, told them to say their prayers to Allah and then shot them.