Police in China have taken to social networking to warn of the dangers of swimming outdoors after at least 15 youngsters died during the weekend from drowning.

The message on Chinese Twitter-like services comes after a number of deadly accidents and is aimed at teenagers who want to take a cooling dip during the summer holidays.

The public security bureau of Fuzhou city, capital of Fujian, posted safety tips on Sina Weibo, the Chinese version of Twitter.

Officers in Zhangjiagang, a brooky area in East China's Jiangsu province, warned against swimming in rivers on their blog.

"Do not let children play near ditches, wells, reservoirs that are dangerous," the Weishan County Police Bureau in East China's Shandong province tweeted.

Six junior high school students died after falling into a river while playing in Central China's Hubei province on Sunday.

Two also died in Yongkang, Zhejiang province, four college students in Erdos, Inner Mongolia autonomous region, and three in Bishan county, Chongqing municipality.

In May, nine students from Guangdong province and two students in Henan province died in drowning incidents.