A stranded pensioner survived after the pontoon he was floating on overturned in the middle of a flood in northern Thailand.

The old man was spotted drifting on a small islet on the swollen river in Nan province on August 12.

A panicked local standing on a bridge called out to warn him of the low-hanging cables about to hit the pontoon. However, as he had no means of steering the pontoon away, it was clotheslined by the live wires.

Footage shows how floating structure toppled over, with the cables emitting bright sparks upon crashing. Miraculously, the stranded man later climbs back up onto the islet seemingly unharmed.

After being rescued, the man told officers that he was securing the pontoon in Ban Wang Wa village three metres away from the bridge when the rope tore and swept it into the river with him still inside.

Officers pulled him out of the flood some five miles down the river near Ban Wang Tao village.

The torrential weather from storm Mulan - which battered China before being downgraded to a tropical depression over Vietnam - caused severe flooding across six Thai provinces.

Department of Disaster Prevention and Mitigation officials said the tropical depression, augmented by a monsoon lying across Myanmar, northern Thailand and northern Laos, caused strong downpours from August 11 to 14.

Thousands of homes across the region were submerged as rescue teams battled to evacuate residents to higher ground, or strengthen flood defences with sandbags. Relief teams were also delivering food and fresh water to residents stranded by the water.

Sandbags were also being used to block the water from spilling into homes and shops while pumps had been brought ini to try and shift the water.

The country's Meteorological Department said Mulan had weakened to a low-pressure cell as it entered Yunnan province in China but the storm has caused widespread heavy rainfall in some of Thailand's northern and northeastern provinces.

Landslides and blocked roads have also been reported across the region as officials try to reach those affected and move them to safe centres.

Thailand and other countries in Southeast Asia such as Malaysia, Indonesia, Myanmar and the Philippines are in the middle of their tropical monsoon rainy season, which lasts until October or November.

Soaring temperatures reaching 35 degrees Celsius are often followed by powerful tropical storms with thunder, lightning, rain and flash floods.

Thailand and other countries in Southeast Asia such as Malaysia, Indonesia, Myanmar and the Philippines are in the middle of their tropical monsoon rainy season, which lasts until October or November.

Soaring temperatures reaching 35 degrees Celsius are often followed by powerful tropical storms with thunder, lightning, rain and flash floods.