Tourists also accounted for a large number of celebrants in famous zones such as Bangkok's Khao San Road and Phuket's Patong Beach.

"We expect the festival to spread up to Bt9 billion all over the country," said Tourism Authority of Thailand governor Pornsiri Manoharn.

South Korean film star Kim Jeong Hoon joined the celebrations in Khao San Road as a special ambassador for Thailand's tourism.

Surrounded by about 500 fans, Kim was on a procession from Khao San Road to Sanam Luang.

By midday, Khao San Road was a sea of water-soaked revellers.

For safety reasons, officials closed all entrances to the road except those at its mouth and end. As part of a plan to tighten security, everyone was subject to a search before entering the backpackers' street.

Earlier in the week, a small bomb exploded in Bangkok, reminding the capital of fatal bombing attacks on New Year's Eve.

Revellers on Khao San Road were barred from playing with talcum powder and high-pressure water guns. Females were encouraged not to wear revealing clothes.

Many people received rebukes from officials after using talcum powder and their powder was seized.

So far, the strict rules have not dampened joyful spirits as celebrants confirmed they were having a great time.

"It's so much fun. I am very happy," an American tourist said cheerfully while engaging in a water fight.

"It's such a wonderful experience," Nisachol Chanabua said about her first Songkran in Bangkok.

Hailing from the northeastern province of Khon Kaen, the girl said the lively atmosphere of Khao San Road was very similar to Songkran celebrations in her hometown.

"The Khao Niew Road has this same feel," she said.

In Khon Kaen, Khao Niew Road attracted a huge number of revellers, including tourists. Up to six stages went up to entertain the water-soaked celebrants with live musical performances.

In Phuket, almost everyone on Patong's beach had a water gun while many roads were closed to traffic to allow revellers to get the fullest fun from the celebrations.

In Nakhon Si Thammarat, fun-seekers took part in water battles in the rain. Some accidents took place.

The grim side of Songkran was the high number of road casualties. On Wednesday and Thursday, road accidents claimed 98 lives, said Interior Minister Aree Wongsearaya. The number of people injured on the first two days of the festival was 1,234.

"Drunk driving was responsible for 40 per cent of 1,067 accidents on Wednesday and Thursday. The number two cause was speeding, which accounted for about 19 per cent of accidents," Aree said in his capacity as chairman of the Road Safety War Room.

There were 632 road accidents on Thursday alone, claiming 57 lives and leaving 720 injured. Most involved motorcycles.

Officials are manning 3,251 checkpoints across the country in a bid to enforce traffic laws and enhance road safety.

Checks on 1,819,299 vehicles so far have led to 38,950 people being punished for breaking traffic laws. The most common offences were failure to carry a driving licence, failure to wear a crash helmet and failure to wear a safety belt.