China said yesterday that at least 400 Vietnamese troop - twice the number reported earlier - have dug trenches and laid barbed wire on a strategic Chinese hill and made raids that apparently penetrated deeper than ever before, up to two-thirds of a mile.

The official New China News Agency, giving new details of the border skirmish that happened Friday, said yesterday that Hanoi's effort to "spy out and nibble Chinese Land" had "aroused great indignation among the Chinese army men and people at the Friendship Pass," the site of the raid.

But the agency did not say what action China would take in response to the most dangerous developments in several months of border strife between the two.

Peking could be handicapped in responding quickly to the Vietnamese moves because Communist Party Chairman Hua Kuo-feng, who as chairman of the military affairs commission also heads the army, is on a state visit to Romania, Yugoslavia and Iran. He is not scheduled to return to Peking until late this week.

Hanoi has not yet responded publicly to the Chinese charge that Vietnamese troops have occupied Chinese soil. The official Vietnamese Communist Party newspaper Nhan Dan yesterday did, however, blame the Chinese for the death of two Vietnamese border officials Friday.

"In the face of the growing seriousness of the incidents and provocations initiated by the Chinese side, the Vietnamese people are enhancing their revolutionary vigilance," the official Vietnamese News Agency quoted the newspaper's "commentator" as saying.

A report from Hanoi last night said the Chinese vice foreign minister representing Peking in talks with the Vietnamese had gone home for consultations. At the same time, Radio Hanoi reported six Chinese boats had been taken into custody for intruding into Vietnamese waters.

Although China had earlier said four ethnic Chinese refugees trying to flee Vietnam were killed by Vietnamese forces in Friday's incident, yesterday the Chinese agency suggested at least seven refugees, including three children, had died.

The Vietnamese may have timed their actions to take advantage of Hua's absence and to test or disrupt the Chinese leadership, or at least lessen the risk of swift retailiation. Hanoi's ally, the Soviet Union, may have tried a similar ploy earlier this year. On May 9 a small force of Soviet troops made a quick raid into northeast China that left several Chinese injured.

Moscow later apologized, saying the troops were chasing a criminal and entered China by mistake, but Peking rejected that explanation. The raid occurred while Hua was in North Korea on his first trip abroad, and Peking appeared to take no action until two days later, after Hua had returned.

The official New China News Agency reported earlier that Chinese border guards had been ordered by higher authorties not to counterattack when Vietnamese troops first invaded the Bonien Hill in Chinese territory late Friday afternoon.

At talks in Hanoi Saturday on the question of the Chinese refugees fleeing Vietnam, Chinese Vice Foreign Minister Chung Hsi-tung said, . . . The Sino-Vietnamese dispute over the question of Chinese nationals can be solved only through negotiations, not by force of arms."

The Chinese and Vietnamese sides at the Hanoi talks Saturday denounced each other for the killings at the Friendship Pass area Friday, but the official Chinese and Vietnamese reports of the session made no mention of Vietnam's alleged occupation of Chinese soil.

The two sides have given widely differing versions of the events in the border area Friday. The Chinese said hundreds of Vietnamese soldiers and police attacked a refugee camp on the Vietnamese side of the border, killing and wounded several of the ethnic Chinese and driving more than 2,000 of them across the border into China. The Vietnamese said hundreds of Chinese police and soldiers in civilian clothes crossed into Vietnamese territory and joined "holligans" among the refugees in an attack on Vietnamese border officials, killing two and injuring several others.

After the bloodshed, according to the Chinese, a force of over 200 Vietnamese soldiers armed with "daggers, pistols, hand-grenades, stick and stones" attacked the Bonien Hill on the Chinese side of the border. By 6:35 p.m. Friday, they occupied it completely, the Chinese news agency said yesterday.

Yesterday's report by Chinese correspondents Chen Szu said the Vietnamese then laid three defense lines: "The first one stretches from the first milestone to Chin Chi mountain with over 200 men. The second defense line is 200 meters behind a hill with 150 men and the last one is 250 meters further behind with 50 men. Throughout the night they dug trenches and laid barbed wire on the Chinese territory. When this correspondent arrived at the Friendship Pass Saturday afternoon, China's Bonien Hill had been enclosed with barbed wire."

The correspondent said he "saw clearly more than 20 Vietnamese army men moving from China's Bonien Hill to the foot of Chin Chi mountain, about 1,000 meters [1,100 yards] within China's territory, to spy out the land."

He said Vietnamese soldiers had also occupied hills on both sides of a Chinese border village called Nung Huai, "several kilometers southwest" of the Friendship Pass. "Over 50 fully armed Vietnamese public security men intruded over 300 meters deep into China's territory to make provocations at the valley northwest of Nung Huai" Saturday morning, the Chinese correspondent said.

More than 160,000 ethnic Chinese residents of Vietnam have fled to China in the last several months. They said they were escaping harsh economic conditions in Vietnam and what appeared to be a Hanoi policy of discrimination against Chinese who might be poor security risks in Vietnam's continuing war with Peking-backed Cambodia.