CALCUTTA, India. Dec. 11—Pakistan refused to let British and Canadian evacuation planes land in besieged Dacca, today, leaving more than 500 foreigners in the East Pakistani capital trapped as potential hostages.

Pakistan's refusal to allow the evacuation came as Indian troops advanced on Dacca in what appeared to he the final drive for complete control of East Pakistan.

When a Canadian Air Force plane from Calcutta—one of four C‐130 transports brought to the Indian city for the United Nations‐sponsored airlift—got within 30 miles of Dacca and asked for permission to land, it was ordered away by the control tower.

According to the pilot, the control tower voice said: “We don't give a damn about U.N. auspices. No plane that has landed in India can come down here.”

The plane returned to Calcutta.

A short time later, according to foreign diplomats here, information reached Calcutta that seemed to indicate that the Pakistanis had relented. One of the transports, a British Royal Air Force Hercules, took off for Dacca. The three other transports taxied out to the runway. But a few minutes later the British plane returned and landed and the others taxied back to the hangar area. The British plane reportedly radioed the Dacca control tower and got the same response the Canadian had on the first attempt.

India is insisting that all planes in the airlift for about 125 Americans and more than 400 other foreign nationals from Dacca must stop in Calcutta on the way in and out.

The Indians say that determining the routes of the planes in this manner is the only way their safety can be guaranteed. But the real reason, independent observers agree, is that India wants to make sure that no Pakistani officials escape on the planes.

Indian Terms Accepted

Neither the Pakistanis nor the United Nations liked the Indian terms, but as of last night, according to diplomatic sources, they had accepted them and the airlift was on.

The diplomatic sources said that Pakistan was now accusing India of using the air cease‐fire agreed on for the evacuation—under which antiaircraft guns would remain silent—to reinforce her troops around Dacca by dropping in infantry and paratroopers by helicopters and planes.

Today marked the third time the airlift had fizzled. The first was last Tuesday when a Canadian plane arrived over Dacca to find itself in the middle of an Indian bombing raid—at a time when there was supposed to be a truce. The Indians said it was a mistake and apologized.

The second attempt came the following day when the same Canadian plane, coming in from Bangkok, Thailand, over the Bay of Bengal, was rocked by antiaircraft fire from a ship. The pilot went back to Bangkok.

Bangla Desh Rally

Meanwhile, officials of the insurgent government of Bangla Desh (Bengal nation) today made their first public appearance in an area cleared of Pakistani troops by the Indians.

The acting president of Bangla Desh, Syed Nazural Islam, the premier, Tajuddin Ahmed, and 128 newsmen in four buses, drove in a motorcade, escorted by Indian troops and Bengali guerrillas, to Jessore, where they addressed a rally of about 5,000.

“I am the happiest man, am in my own free motherland,” Mr. Nazural Islam, placing his right hand over his heart, said to a newsman during a stop on the road to Jessore.

In Jessore, which was taken by the Indians last Tuesday, the acting president told the crowd: “We will not tolerate anyone who tarnishes the relationship between India and Bangla Desh.”

He added: “There will be no more politics based on religion from now on, no more religious parties [a reference to the rightwing Moslem parties that support the Pakistani Army].”

The crowd was polite and mildly enthusiastic, but it was a pale version of the vibrant throngs that used to come to listen to Sheik Mujibur Rahman, the leader of East Pakistan. He has been imprisoned in West Pakistan since March, when Pakistani troops swept into the east to try to wipe out the Bengali autonomy movement.

Though Jessore has been free of the Pakistanis for only four days, the people have plastered Mujib posters on nearly every building. Bangla Desh flags were doing a brisk sale.

About 1,200 non‐Bengalis, including women and children, are being kept in the Jessore Central Jail for their protection. These non‐Bengalis, most of them Biharis, had sided with the army.

Premier Ahmed said that as soon as civil administration was established in an area, “there will be no need for the [Indian] army to stay.”