The clean-up of an oil spill from a bulk carrier run aground in the Solomon Islands could reach $50m, experts have said, as efforts began to prevent more oil leaking into the sea.

Eighty tonnes of heavy fuel oil has leaked so far in an area close to a world heritage coral site on Rennell Island.

An estimated 600 tonnes remains onboard the MV Solomon Trader and operations began on Friday to pump the fuel from the ruptured tank into a secure container.

It will then be transferred onto a barge expected to arrive at the site on Saturday. The transfer was expected to take two days.

The bulk carrier’s Hong Kong owner, King Trader Ltd, and the vessel’s South Korean insurer issued an apology over the environmental disaster but stopped short of accepting liability.

The ship had been loading bauxite from a mine in the days before Cyclone Oma pushed it aground on a coral reef in the early hours of 5 February.

Australian Maritime Safety Authority officials on Friday began setting up a four-tonne dynamic boom system brought from Brisbane to start cleaning up the oil that has already spilled into the sea.

Two other Australian vessels were en route with further equipment and were due to arrive on Sunday.

The companies involved with the Solomon Trader were expected to take over the clean-up operations next week. The Australian authorities would then pursue them for the cost of its clean-up efforts.

Shipping experts estimated the overall clean-up costs to be between $30m-$50m.

Australia has been keen to ensure international shipping companies do not shirk their responsibilities for maritime incidents in Pacific island nations.

The Solomon Island’s caretaker prime minister, Rick Hou, was also talking tough – threatening to blacklist the companies involved in the leak.

“My government is prepared to go as far as putting the companies on a black list internationally if they do not take on their responsibilities,” he told reporters.

The Solomon Islands maritime safety administration said it was investigating a possible breach of the international safety management code because of a “lack of a crew posted on lookout/watch during that night”.

A shipping expert has warned there could be huge insurance ramifications for a code breach including insurers walking away from a claim. This could create headaches over who gets stuck with the cleanup bill.

Reports of the Solomon Trader “crew being absent from the vessel or intoxicated at the time of the grounding are false”, the ship’s owner and insurer said in a statement this week.

The vessel has run aground before – 17 years ago the Greek-flagged Doric Chariot was hauling coal from Mackay to India when it hit Piper Reef in the world-heritage-listed Great Barrier Reef.