New documents have emerged detailing tens of thousands of dollars being paid by an Australian company to the family of Nauru's Justice Minister, David Adeang.

The bank records reveal monthly transactions from the account of the phosphate company Getax, which was formerly based on the Gold Coast.

The Australian Federal Police (AFP) are investigating the company for the alleged payment of bribes to Nauruan politicians, in an effort to access the island's deposits of rock phosphate.

7.30 first revealed the apparent arrangement last year, after obtaining emails which suggested Getax was sending money to Nauru a number of politicians, including Nauru's current President Baron Waqa and Justice Minister David Adeang.

Those emails were dated from 2009 and 2010.

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Regular payments described as 'consultancy fees'

Nauru's Justice Minister, David Adeang. ( Department of Foreign Affairs and Trade )

The latest documents obtained by 7.30 include bank statements confirming payments to politicians were already being made in 2008.

Amounts of $10,000 were transferred on several occasions from Getax's Westpac account into the ANZ bank account of Madelyn Adeang, the late wife of Minister David Adeang.

The payments were described as "Consultancy fees", or "Fees for Adeang".

The transactions included:

$20,000 in April 2008

$20,000 in April 2008 $10,001 in June 2008

$10,001 in June 2008 $10,000 in July 2008

$10,000 in July 2008 $10,000 in September 2008

$10,000 in September 2008 $10,000 in October 2008.

The Nauruan Government did not respond to 7.30's inquiries about the payments.

It has previously denied allegations of bribery involving Getax, describing the claims as "baseless".

The co-chair of the International Bar Association's anti-corruption committee, Robert Wyld, says the evidence appears clear.

"There appears to be a very compelling case to evidence what a businessman or company has tried to do, and that is to pay money to politicians to secure a business deal," he told 7.30.

Madelyn Adeang died in 2013.

Several Nauruan sources have told 7.30 she was not involved in any consultancy work for Getax.

The phosphate company is now believed to be operating in Dubai.

'A parade of unsavoury-looking incidents'

Chairman of Transparency International Australia and former Supreme Court Judge, Anthony Whealy, says the payments to the Adeang family look unsavoury.

Transparency International Australia Chairman, former Supreme Court Justice, Anthony Whealy QC, has called on authorities to expedite their investigation.

"Transparency International is very concerned about all instances of foreign bribery and there have been plenty of them lately," he said.

"This is one more in a parade of very unsavoury-looking incidents."

The AFP have been investigating the case for several years.

Mr Whealy says the lack of action may be viewed by some as a political decision, due to the Australian Government's deal with Nauru for offshore immigration processing.

"There is a perception that perhaps the Government doesn't want this sort of investigation to come to anything much," he said.

"Now that's probably an unfair suspicion, but it's certainly there and it will linger, and the longer it takes to get a prosecution under foot the more Australia's reputation will suffer."

The operators of Getax did not respond to the 7.30's inquiries.