The headquarters of the Monaco-based oil company Unaoil and the homes of its executives have been raided by police in the wake of revelations in recent days that it has systematically corrupted the global oil industry.

In a statement, the Monaco government said it was helping British authorities investigate the "vast corruption scandal" revealed in recent days by Fairfax Media and The Huffington Post.

Police moved after Fairfax Media broke the story late on Wednesday that Unaoil and its owners, the Ahsani family, used multi-million dollar commissions to bribe corrupt governments in oil rich states to win contracts for large western firms such as Rolls-Royce, Halliburton and Australia's Leighton Offshore.

The statement from the Monaco government said that several of the company's senior executives had been questioned over the past few days and their homes and headquarters searched following an urgent request from Britain's Serious Fraud Office.

"Monaco authorities conducted searches of the homes of the leaders of the company Unaoil and at its headquarters in the Principality," the statement said.

"The leaders of this company were also interviewed on 29 and 30 March 2016. These searches and interviews were conducted in the presence of British officers, in connection with a case of vast corruption with international ramifications that involves many foreign companies active in the petroleum sector.

"The items collected during the search will be now be used by the British authorities in their investigations."

Fairfax Media revealed on Thursday that the British police had teamed up with the Australian Federal Police, the US Department of Justice and the FBI to investigate the vast cache of emails on which our stories have been based.

The Monaco government said it would not release further details at this stage in case it compromised the investigation.

A spokeswoman for Unaoil told Associated Press the company "has no comment at this time". The Serious Fraud Office also declined to comment.

In Australia, Opposition Leader Bill Shorten said the revelations were "tremendously alarming".

"I'm grateful for the lid being ripped off some of those carryings on of multinational companies engaging in global bribery," Mr Shorten said on Friday.

"When it comes to anti-corruption, Mr Turnbull's always out there bashing the unions, but he's been disappointingly silent on the conduct of Australian multinationals engaged in global bribery.

"Mr Turnbull needs to be tough on multinationals as much as he's willing to be tough on schools and hospitals. So we take it very seriously, the revelations are deeply disturbing and we won't let this issue go."