Bangkok residents are continuing mass exodus from the capital

The Thai authorities have asked US military helicopters to survey flooding, which has hit the north and is now threatening the capital Bangkok.

Two Seahawk helicopters aboard the USS Mustin warship would conduct "aerial reconnaissance", the Pentagon said.

The warship is docked at the port of Laem Chabang, just south of Bangkok.

Thai officials say high tides due on Saturday and the flow of run-off water from inundated central plains could cause wider flooding in the capital.

City residents are continuing mass exodus, after the authorities urged them to leave Bangkok.

Heavy monsoon rains have been causing flooding in Thailand since July. More than 370 people have been killed and swathes of the country affected.

Thai U-turn

John Kirby, the captain of the USS Mustin, said Thailand had asked the warship to prolong its stay at the port for up to six days.

"The Thai government has asked to have it stick around to help out," he told reporters on Friday.

The destroyer docked at Laem Chabang a few days ago for what expected to be a week-long sting.

The Thai government had initially said it did not require assistance from the US navy with flood relief efforts.

Meanwhile, water levels in Bangkok's Chao Phraya River river hit a new high - 2.47 metres above sea level - as residents continued to leave the capital ahead of possible flooding.

Authorities fear that the river, which bisects Bangkok, could burst its banks when water levels rise because of unusually high seasonal tides over the weekend.

Flood waters are continuing to creep into northern districts of Bangkok but the centre remains mostly dry.

Roads in and around the capital remained jammed as residents used a five-day holiday to leave the city.

Prime Minister Yingluck Shinawatra said she was assessing a proposal to dig channels into some roads in eastern Bangkok to help water drain through to the sea.

Supply chain affected

On Friday, the Bank of Thailand slashed its growth forecast for the current financial year to 2.6%, down from an initial projection of 4.1% growth.

The flooding is also disrupting global supplies of computer hard disk drives and car parts.

A number of factories in Thailand - one of the world's leading manufacturing bases - have shut down production, and it is now yet known when they will become operational again.

Among the affected companies are Toyota Motor, Honda Motor and Lenovo Group Ltd - one of the biggest computer makers.

Apple chief executive Tim Cook has warned that he is "virtually certain" that the flooding will lead to an overall industry shortage of hard disk drives.

"Like many others, we source many components from Thailand," he was quoted as saying by the AFP news agency.