Oily Aussie protesters in bikinis oppose spill in Timor Sea

The spill started on August 21 at PTTEP Australasia's Montara oilfield more than 200km off Western Australia's Kimberley coastline.

Attempts to intersect the leaking oil well and plug it with heavy mud have so far been unsuccessful.

On Thursday Thai-based company PTTEP said the cost of the spill had mounted to $177 million and its clean-up bill was more than $5 million so far.

A further bid to intercept the leaking well is planned for the weekend but ALERT Well Control, the company plugging the well, says it could take three more attempts and several more weeks.

Supporters of The Wilderness Society staged a protest outside the headquarters of the Australian Petroleum Production and Exploration Association on St George's Terrace on Friday.

The colourful protest included beating drums, with about 50 protesters chanting "never again".

Wilderness Society WA marine co-ordinator Jill St John told onlookers that Australia had become complacent about its marine environment.

Dr St John said Australians had fought to protect the Great Barrier Reef from the oil and gas industry 40 years ago but seemed to have forgotten the marine environment was worth more than oil and gas.