More than 300 people have been killed in the worst flooding to hit the country in decades.

The army and volunteers are working to shore up flood defences in Bangkok but there are fears barriers will not hold.

Officials said earlier this week that the capital would be safe.

The government of Prime Minister Yingluck Shinawatra has been criticised for giving what many in Thailand say has been unclear or conflicting information about the disaster.

At a news briefing on October 19, Ms Yingluck - who came to power in August with relatively little political experience - said her government had "done everything to the best of our ability" and asked for support from the public and media.

The northern Thai provinces of Ayutthaya, Pathum Thani and Nakhon Sawan have already been devastated by flooding.

The Bangkok districts now on alert are Sai Mai, Khlong Sam Wa, Bang Khen, Nong Jok, Min Buri, Lat Krabang and Kan Na Yao, all to the north of the capital.

The Thai air force has moved some of its planes from Don Muang international airport, by Sai Mai district, as a precaution.

Bangkok is criss-crossed by small waterways, and the warning came after several key sluice gates were opened to allow water to flow into the major Rangsit canal, which runs from the Chao Phraya river through Patum Thani.

Some 1.2bn cubic metres of water was expected to enter the Rangsit canal, said Bangkok Governor Sukhumbhand Paribatra.