Sydney  - A Thai oil exploration company said Sunday its leaking Timor Sea oil well had caught fire.

The West Atlas drilling platform operated by PTTEP Australasia in the Montara field 690 kilometres west of Darwin has been leaking around 400 barrels of oil and gas a day since August 21.

The company brought in a mobile rig from Indonesia to drill 2.6 kilometres into the seabed to try and intersect the leaking well and plug it with drilling mud.

Three earlier attempts had failed but there was success early Sunday when the drill hit its mark and heavy mud was pumped in to seal the well off, it said.

But only hours later, PTTEP announced a fire had started and that the West Atlas rig and the Montara well head platform were burning.

Conservation organization WWF has reported that the slick could cover up to 15,000 square kilometres. Due to a 40-kilometre exclusion zone, WWF can only estimate of the scale of the pollution.

The Australian Maritime Safety Authority has been flying C-130 Hercules aircraft from Darwin each day to drop dispersant over the slick. The authority said it had 300 staff working on the clean up. (dpa)