Vietnamese forces have seized three positions at Liaochang in China's southern province of Kwangsi, the official New China News Agency said today.

The agency, in a dispatch monitored here, said Vietnamese early Wednesday "lobbed on shell at a Chinese outpost on the border and the shell landed on meter off the outpost. Later, more than 40 armed Vietnamese intruded into China and took three heights in Liaohang."

The Vietnamese later "fired over 30 rounds from one of the heights at Panchiu village, in Liaohang area, wounding seriously Liang Chien, a member of the Chinese patrol team," the agency reported.

The area where the alledged attack took place is near Vietnam's northern border. There was no response from Hanoi.

The Chinese Foreign Affairs Ministry lodged a strong protest with the Vietnamese embassy in Peking accusing Vietnam of "encroaching on Chinese territory" and creating "new and grave incidents," the dispatch said.

The reported attack came after China's Vice Premier LiHsien-nien accused Vietnam of serious provocations and sternly warned that "China's forebearance has its limit."

Some diplomats said the strong language in the protest and in Li's warning was similar to that contained in protest notes delivered to India before the Chinese took massive military action on the Sino-Indian border in 1963.

Li's remarks, reported by Peking Radio, came in talks with Maj. Gen.Chatichai Choonhavan, a former foreign minister of Thailand who is visiting Peking.

"China's forebearance has its limits and the Vietnamese authorities are deluding themselves by thinking that we are weak and can be bullied," Li said.

Vietnam is involved in a protracted border dispute with China, which also supports Cambodia in its conflict against Vietnam. The Vietnamese have Soviet support. The Soviet Union has announced public support for a Vietnamese-backed insurgent group operating out of "liberated zones" in eastern Cambodia.

[Meanwhile, in East Berlin, the East Germans news agency ADN said Vietnam lost more than 3 million tons of rice in heavy floods that swept the country in October.]