Deputy Public Health Minister Surawit Khonsomboon confirmed on Sunday that altogether 12 were killed while 129 people wounded in a petrochemical factory accident in Map Ta Phut industrial estate in Rayong province, east of Bangkok.

Local media formerly reported 13 for the figures of death toll and 105 for the injured.

Of the twelve, nine died immediately at the accident site, according to Surawit. Until now 99 out of overall 129 injured had been already released but 30 still remained for further treatments at hospitals in the east coast province, he added.

The deputy health minister also elaborated that the costs of medical treatment for those victims would be taken care by the government under the national healthcare schemes.

The explosion occurred at a unit of Bangkok Synthetics Co (BST) inside the Map Ta Phut industrial estate at about 3.30 p.m. on Saturday, followed by a fire which was put out completely later on early Sunday morning.

Meanwhile, Industry Minister Pongsvas Svasti said he had ordered the closure of the factory where the explosion occurred. He also instructed other factories in the industrial estate to recheck their security systems since the operations of more than half of them concern chemicals.

Thousands of people in communities around the industrial estate were evacuated urgently after the Saturday's incident.

Accompanied by Interior Minister Yongyuth Wichaidit and Industry Minister Pongsvas Svasti, Prime Minister Yingluck Shinawatra flew Sunday morning to Rayong province in order to inspect the factory and people wounded.

The PM ordered agencies concerned to closely watch the situation to prevent chemical leakage and frequently examine water and air quality in the surrounding areas, home to about a dozen communities.

An environment officer at BST said that toluene might have caused the fire after being exposed to excessive heat.

The industry minister said that people could possibly return their homes today as the air quality test showed level of hydrocarbon in the air was normal.

The assessment of damage cost was not yet reported.