The Australian Federal Police (AFP) say that they are working with international law enforcement agencies to investigate companies linked to Malaysia's state fund, 1Malaysia Development Berhad (1MDB).

Australia has just joined six other countries, which includes the US, Singapore and Switzerland, in opening investigations into money laundering allegations involving the sovereign fund.

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So far only Singapore has charged people for their involvement in transactions linked to 1MDB. Four people have been convicted and sentenced to jail terms.

The US Department of Justice has brought a civil suit to recover funds after claiming that more than $3.5bn had been misappropriated from the state fund. It is seeking to seize $1bn in assets it claims were bought using funds diverted from 1MDB to buy luxury real estate, valuable paintings and even a private jet, Reuters reports.

Najib Razak
Malaysia's Prime Minister Najib Razak Rosland Rahman/ AFP

In an emailed statement to the news agency, the police said: "AFP is responsible for investigating breaches of proceeds of crime laws by Australian companies, citizens and residents.

"The AFP is aware of allegations relating to companies associated with 1MDB and have assisted our foreign law enforcement partners with their investigations in relation to a number of these matters."

It said it that as it "continues to evaluate these allegations, it would not be appropriate to provide any further comment at this time".

The Australian police did not say if they were investigating whether any financial gains were made in Australia, nor did they specify which international agencies they were working with.

The 1MDB scandal has been described as one of the largest in financial history. Billions were allegedly siphoned from the fund into personal bank accounts. Malaysian Prime Minister who founded the fund and was the . Najib Razak. Razak, who had denied all accusations, has been cleared of any wrongdoing by the Malaysian authorities.