Cambodian authorities today ignored a plea and protest march by about 150 Western celebrities and relief workers for the opening of a truck route into Cambodia for food and medical supplies.

The group of men and women walked to the Thai side of a barricaded bridge and conveyed their request by bullhorn. They sought entry for a special convoy of 18 trucks loaded with relief aid.

There was no response to the request by the men in soft caps and green uniforms who peered at them from the Cambodian side.

The marchers included such personalities as folksinger Joan Baez, Soviet poet Alexander Ginzburg and the mayors of Paris and five other French cities.

"This is a major effort to persuade people of the urgency of doctors, nurses and medical supplies being brought into Cambodia," Baez told reporters. "It does not address itself to politics or warfare."

The march, however, was dismissed by many other relief groups as provocative and founded on misinformation. It also coincided with recent statements by United Nations officials that food and health conditions in Cambodian have improved significantly.

Organizers said today's demonstration was intended to revive flagging world interest in Cambodia, to press Phnom Penh to accept foreign doctors and to open a "land bridge" for trucks. Many aid workers feel a truck route would be the most efficient way to distribute emergency supplies.

However, officials of Cambodia's Heng Samrin government viewed the march as an attempt to blame their government for food and health problems in Cambodia. The official news agency announced in strong terms beforehand that neither the marchers nor their trucks -- waiting this morning a half mile back from the bridge -- would be allowed to cross.

Thai military officers at the bridge said that in recent days Heng Samrin troops had strengthened barricades on the single-lane bridge, closed off since Thai and Vietnamese troops traded gunfire across it last spring, New mines were laid on the Cambodian side and holes dug in the road, the officers said.

Carrying a banner reading "Please allow us to help the people of Cambodia," the marchers reached the border bridge late this morning. About 200 yards inside Cambodia, one dozen men, some in green uniforms, some in civilian dress, could be seen watching the group. Most of those in uniform wore the soft caps of Heng Samrin's Cambodia forces. A few, however, had on green pith helmets of the type issued to Vietnamese troops.

Three representatives of the march stepped up to the bridge and through a red bullhorn read 90-second pleas in French, English and Cambodian for permission to bring in the supplies. Soldiers on the other side moved closer, some to take pictures, others apparently to hear more clearly. But they did not respond to the request.

The demonstrators had not expected a positive answer -- Baez, for instance, said she did not bother to bring her passport. Later, they left the bridge to visit refugee camps on the Thai side of the border. If no affirmative response is received by Thursday, the 18 truckloads of supplies will be turned over to the Thai Red Cross for distribution among refugees and Thai citizens displaced by the Cambodian upheaval.

The march was sponsored by the American-based International Rescue Committee and the French Doctors Without Borders organization.