Caretaker Solomon Islands Prime Minister Rick Hou is threatening to blacklist the companies involved in a 100-tonne oil leak near a UNESCO World Heritage site.

Key points: An expert warns Solomon Islands lack expertise to clean up the spill

An expert warns Solomon Islands lack expertise to clean up the spill Prime Minister is considering banning companies involved ahead of election

Prime Minister is considering banning companies involved ahead of election The ship has been leaking oil since it ran aground a month ago

"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 said at a media conference yesterday.

Mr Hou, who faces an election on April 3, has sought Australia's assistance to clean up the oil spill, which he described as causing "irreversible damage", after acknowledging his country's resources were inadequate for the task.

"The ecological footprint of the whole bay is already devastated with much of it unlikely to recover," he said.

"The impact on the marine life and the coral is already massive with much of it irreversible."

The bulk carrier MV Solomon Trader ran aground on a reef near the remote island of Rennell in the south of the Solomon Islands over a month ago while attempting to load bauxite from a nearby mine in poor weather.

The MV Solomon Trader ran aground on a reef at Lavangu Bay in East Rennell while trying to load bauxite on the island. ( ABC: The Australian High Commission )

A Solomon Islands bid for an insurance payout from the ship's owners is likely to be delayed, with the country not party to a key maritime treaty that allows payouts directly from insurance companies.

Professor Craig Forrest from the marine and shipping law unit at the University of Queensland said because the Solomon Islands was not a signatory of the International Convention for the Prevention of Pollution of Ships, its options were very limited.

"The Solomon Islands cannot go directly to the insurer, so the only entity they can look to is the ship's owner," he told the ABC.

We get nothing from mining, PM says

The MV Solomon Trader ran aground on a reef at Lavangu Bay in East Rennell. ( Supplied: Australian High Commission )

Mr Hou said tax concessions to the miner meant the Government had earned next to nothing in tax.

He also said that while authorities were struggling to contain the oil spill and salvage the wrecked vessel, the company, with the support of local chiefs, was continuing to mine and ship bauxite out of the country.

"It is my government's view that exporting our resources for virtually no economic [return] is immoral and unacceptable," he said.

Indonesian company Bintan Mining, which chartered the ship, has previously said it has done all it can to assist recovery efforts. The ship's insurer, Korea Protection and Indemnity Club, and owner, King Trader Ltd, both issued a statement this week apologising for the spill.

"Although matters of liability are yet to be determined, the vessel's protection indemnity insurer and the owner have expressed deep remorse," the companies said in a statement.

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Footage taken this week shows little progress has been made in stopping the flow of oil since the ship ran aground.

International lawyer and Solomon Islands fisheries expert Transform Aqorau said the scale of the disaster was unprecedented in the island's history.

"It's the worst environmental man-made disaster and we have never experienced something like this," he told the ABC.

A DFAT official told reporters Australian support was on the way, with two Australian vessels scheduled to arrive on Sunday to help with the clean-up.