With temperatures at near-record highs, Thailand began celebrating the week-long water festival known as Songkran even as the military regime urged people to save water and keep their clothes on.

Although the country is suffering its worst water crisis in 20 years, Thais joined their neighbours in Laos, Cambodia and Myanmar in welcoming in the Buddhist New Year, visiting temples to earn "merit" yesterday.

In Bangkok, Governor Sukhumbhand Paribatra led city officials in a ceremonial offering to monks at the sprawling Sanam Luang grounds under the spires of the Grand Palace. Monks carried a sacred Buddha image from the adjacent National Museum for people to pour water on.

From around 10am, police closed certain streets to vehicles. City officials appeared on Silom Road early yesterday, telling vendors not to sell big water guns or large containers of water, and urging people to use light handheld garden sprayers instead. They inspected iceboxes for alcoholic drinks, which were prohibited.

But by mid-afternoon, all efforts at self-discipline vanished. Raucous throngs flooded the street armed with water guns and soaked each other to the beat of pounding music.

The junta had earlier threatened to arrest women who dressed scantily or engaged in "sexy dancing", a common occurrence as the nation celebrates the year's longest holiday. In Chiang Mai, police arrested a shirtless foreigner and fined him 100 baht (S$4) for violating the ban on indecent dress.

The water crisis has forced the government to pump out the muddy bottoms of reservoirs as they dry up. In Sukhothai, the temperature hit 44 deg C this week, nearing the highest ever recorded.

Reports said some celebrations in provinces in the north-east, which has been badly hit by water shortage, were subdued. But elsewhere the drought did not deter "water tunnels'' - twin rows of fountains that soak pedestrians - which were set up at several places, including in the southern city of Pattani and on the Thai-Myanmar border at Singkhon, south of Bangkok.

In Yangon, Myanmar's former capital, which has also experienced soaring temperatures amid a major drought, the festival is called Thingyan, and is considerably rowdier than in Thailand. Main roads in the city centre and the banks of Inya Lake were packed with revellers pounding out loud music and soaking each other with hoses, buckets and water guns.

With millions on the move to visit families up-country, Bangkok's streets saw only light traffic. But across Thailand, the death toll on the roads, mostly from drink driving, reached 116, with another 981 injured in 907 accidents on Monday and Tuesday, which are counted as the first two days of the holiday.

Despite the Thai police's tough new measures against drink driving, the figure was nearly double last year's count for the same period.