Thailand put its army on alert yesterday and accused neighboring Cambodia of an "uncivilized, inhuman and brutal" attack on three border villages over the weekend that killed 30 persons.

Thailand closed its only official border crossing with Cambodia after the Friday attack and lodged a protest with Cambodian officials. Deputy Prime Minister Boonchai Bamrungphong said that if Cambodia does not respond, Tailand will take the issue to the United Nations.

The army alert followed an emergency meeting of the supreme military command here, and could plummet the already-strained relations between Thailand and Communist-ruled Cambodia to a new low. Boonchai told a news conference the army would be used only "if the border patrol police prove inadequate" in coping with future attacks.

Boonchai said since the Khmer Rouge victory in Cambodia nearly two years ago, Communist troops have crossed into Thai territory "more than a hundred times," but that since the raids were limited to a few men seeking food or medical supplies, "We didn't protest."

He said the latest raid was a full-scale attack by between 200 and 400 troops armed with rifles, grenades and rockets. Only 18 Thai border police were in the area of the three villages a few miles south of the official border crossing at Aranyaprathet.

Officials said the attackers burned houses, destroyed stored crops and killed 29 villages, including 22 women and children. One Thai border policeman also was killed, officials said.