Authorities said an Internet message warning of disasters was a hoax, while officially forecasting that the capital could receive the normal amount of precipitation this year.

The message, which caused concern online, claimed that the US National Aeronautics and Space Administration (Nasa) had issued a warning about extraordinarily heavy rain in Thailand this year due to the warm ocean current caused by El Nino.

The warning also said Bangkok and coastal areas would face a gigantic flood in September, which would rise as high as four-storey buildings, and the country would also be hit by a super tornado.

“This faulty information has been spread over and over again on the Internet. Many people worry about it and call our department. There is no possibility of Bangkok facing such a big flood and we are not in a tornado region,” Wanchai said.

He said El Nino was a phenomenon where the surface of the eastern Pacific Ocean became warmer than usual and caused the Americas to experience heavy rain and floods. In that situation, Southeast Asia faces arid conditions similar to those during the major drought two years ago.

Wanchai forecast that flooding would be a moderate in Thailand this year, as the weather prediction model indicated that the country would receive about 10 per cent more rain than average and there would not be a big flood such as in 2011.

“The situation this year differs from 2011, as that year we faced a La Nina situation, which caused greater rain than usual in the region. Moreover, we expect to face two tropical storms this year, which is average,” he said. “There will be floods in the low-lying area of the Central Plain, but this is a natural phenomenon that occurs every year and people should not panic. If the department discovers any threat of natural disaster, we will inform the public immediately.”

He said recent heavy rains in Bangkok were a result of a southwestern monsoon, which was normal during the rainy season.