The company responsible for an oil and gas leak that sparked a fire at an oil rig last week is preparing a $170 million insurance claim to cover its costs.

A well in the Montara oilfield off the WA coast was plugged last week after leaking into the Timor Sea for 10 weeks.

A spokesman for the operator, PTTEP Australasia, told insuranceNEWS.com.au the company has made a provision of $170 million in relation to the incident. This figure is already under review following the fire on the Montara wellhead platform.

He says PTTEP will also cover the clean-up bill for the spill, which was carried out by the Australian Maritime Safety Authority and cost an estimated $5.3 million.

Thai-based parent company PTT Exploration and Production Public Company has told the Thai Stock Exchange it has insurance coverage of $US270 million ($296 million) and is in the process of claiming all expenses related to the damages, which will be booked as income in the next quarter.

The company refused to disclose its insurers.