BEIJING : Fifteen people have been killed and four are missing after torrential rain in southwest China, state media said Wednesday.

"The latest round of torrential rains since Monday had killed 15 people and left four others missing in southwest China's Chongqing Municipality as of 7 am Wednesday", state news agency Xinhua said, citing local authorities.

The confirmation of casualties comes after officials on Tuesday put in place an alert for rain-triggered disasters across large swathes of central and southwest China.

President Xi Jinping has ordered that "authorities at all levels must give top priority to ensuring people's safety and property", Xinhua said Wednesday.

"Xi underlined that leading officials at all levels must take the lead in fighting the floods, put the people's safety and property first, and strive to minimize all kinds of losses," Xinhua added.

In a sign of how extensive the damage is, workers on Tuesday discovered that a closed-off railway bridge on the outskirts of Chongqing had collapsed after it was "damaged by the impact of mountain torrents", state broadcaster CCTV said.

In neighbouring Sichuan, authorities said more than 460,000 had been affected by the heavy rain this month, Xinhua reported.

About 85,000 people have been evacuated from their homes as a result of the rain, officials said, with "flash floods in mountainous areas" and "possible mudslides in some parts" of the country expected this week.