More than 10,000 vehicles have been busted over the past 12 days for emitting black exhaust fumes that exceed the safety limit, says the Department of Land Transport (DLT).

Somchai Ratkaew, an inspector with the DLT's Land Transport Supervision Division, said Thursday that 13 exhaust fumes inspection checkpoints, jointly run by the DLT and traffic police, were set up and have been operational in Bangkok and surrounding provinces since Jan 27.

"Until now, more than 10,000 vehicles have failed exhaust smoke tests," Mr Somchai said.

Thursday morning, a bus and 10 cars were impounded for spewing out black smoke that exceeded the safety limit at a checkpoint on Lat Krabang Road, said Mr Somchai, who was at the site.

The bus owner will face a fine of between 5,000 baht and 50,000 baht, he said. Regarding the owners of the impounded cars, traffic police fined them 1,000 baht each, Mr Somchai noted.

As for criticism by some busted motorists that their vehicles had passed exhaust smoke tests at the DLT, Mr Somchai said the test devices used by both the DLT and officers manning the checkpoints are the same and the officers also use the same threshold.

However, some of the vehicles might have been carrying more weight during the latter inspection which could have accounted for the difference, he said.

Meanwhile, Thai authorities have reportedly asked their Myanmar counterparts to seek cooperation from locals in Phayatongsu town, opposite Sangkhla Buri district in Thailand's Kanchanaburi province, to stop forest burning to prevent dust from the sites blowing over the border.

Myanmar officers agreed to deal with the issue, saying they have already rolled out regulations and sought cooperation from local people to refrain from burning forested land to hunt animals or clear it for farming, according to a source who attended the meeting.

In Kanchanaburi, governor Jirakiat Phumsawat presided over the start of a campaign to encourage people to stop burning land. Farmers there are known to use slash-and-burn techniques.