HONG KONG (AP) _ Vietnamese troops torched Chinese forests along the border this week after an exchange of gunfire between the two countries near disputed islands in the South China Sea, an official report from China said.

The fire began Wednesday near the Guangxi autonomous region border town of Pingxiang, the domestic China News Service said in a report appearing in Hong Kong today. Chinese troops battled the blaze throughout the night, finally putting it out early Thursday, the report said.

It was the 25th time in the past five years that Vietnamese troops situated across the Pingerguan Pass had set fire to Chinese forests across the border, the news agency said.

The report accused the Vietnamese of attempting to use northwesterly winds Wednesday to fan the fire and ruin Guangxi's Taqingshan forestry center during tree planting season. It said Chinese troops saved 500 acres of forest with the help of a 3,000-yard fire lane built in July.

The report did not say how much of the area was destroyed by the fire.

Tension between the neighboring Communist countries has been mounting since gunfire was exchanged between Chinese and Vietnamese vessels near disputed islands in the South China Sea on Monday.

China acknowledged Wednesday it suffered an unspecified number of casualties in the clash, and Vietnam said three of its vessels were burned in the encounter in the Spratly Islands.