NEW DELHI, April 4—The Pakistan radio has charged that nine Indian vehicles loaded with arms and ammunition crossed the border into East Pakistan and were stopped by West Pakistani troops.

The broadcast, late last night and again this morning, said the vehicles were stopped on their way through Thakurgaon, a town in the northern part of East Pakistan 20 miles from the Indian border. The radio did not say when the vehicles were stopped.

The Indian Government has denied sending any military equipment to the East Pakistanis, who have proclaimed their independence and are fighting West Pakistani soldiers.

Late tonight, East Pakistani “liberation forces” were reported to have recaptured the town of Dinajpur after a daylong battle against West Pakistani soldiers.

Efforts were under way in the Indian state of West Bengal, which borders on East Pakistan, to organize aid for the East Pakistanis. Several groups of volunteers have reportedly crossed the border with supplies of food, medicine and some ammunition.

Senior officials in Calcutta said privately two days ago that discussions for organizing an underground arms and supply network were under way, and they expressed strong support for the project.

“It is inevitable and of course we will never admit it,” one high Government official in Calcutta said in an interview. He said it would be politically dangerous not to help because most of the people on both sides of the border are Bengalis, and support in West Bengal for the East Pakistanis has been virtually unanimous.

Border guards in West Bengal have been ordered to turn back what they consider to be “thrill‐seeking teen‐agers” at tempting to cross into East Pakistan. But the border is so loosely patrolled that it is unlikely that those determined to cross could be stopped. There have been numerous reports of Indian border guards turning their backs on those crossing the border with supplies.

Prime Minister Indira Gandhi said today that while India did not interfere in the internal affairs of other countries, it was not proper nor possible to re main quiet on events in East Pakistan.

Speaking in Hindi to national committee members of the ruling Congress party, Mrs. Gandhi said: “We must act in constructive way to see that we do not do anything that adds to the difficulties of the people there.”