Six workers were injured, two critically, when the boiler, in which old tyres are being heated and melted, exploded in a factory in Podanur on the outskirts today.

The factory, in Chettipalayam, was engaged in extracting oil by melting old tyres in a high point in boiler, police said.

The workers, who were putting tyres through the boiler door, noticed that no smoke was emanating from the top and went near to check. However, it exploded with a big noise, resulting in burn and splinter injuries to six workers, police said.

All the injured, hailing from Assam, were admitted to the Government Hospital here, where the condition of two workers was said to be critical.

According to police sources, the factory had been functioning without getting a proper permission from the district administration. The owner of the factory and his son are currently absconding.