BEIJING - FLOODS blocked roads in southern China, leaving some 300 teenagers stranded at a school with limited supplies of food and water, an official said on Sunday, after days of heavy rain killed at least 16 people.

More than 320,000 people have fled their homes in southern and central China after heavy rains toppled houses, flooded roads and damaged a dam, news reports said.

Flood waters blocked the entrances to the Hemu Town Middle School in the Guangxi region and rendered nearby roads impassable, according to an official of Rongshui county where the school is. She would only give her surname, Lu.

CCTV said on Sunday that floodwaters along a major commercial thoroughfare elsewhere in Rongshui were more than 8 feet (2.5 metres) deep. The report said it was the highest water level the county has seen in a decade.

Flood control officials used boats to deliver food, mineral water and other supplies to the school on Saturday, including pumps to lower the water level, Ms Lu said.

She said she did not know how long the children, aged from 13 to 15 years, had been stuck in the building.

Heavy rains have battered the region since Wednesday. By Friday, 80 per cent of the county was inundated, causing the Rongjiang river to overflow its banks and forcing the relocation of more than 70,000 people, Ms Lu said.