Two men in their 20s who worked at the Australian Bureau of Statistics and the National Australia Bank have been charged with insider trading on foreign currency markets.

The Australian Federal Police (AFP) alleges 26-year-old former NAB employee Lukas Kamay, based in Melbourne, used unpublished unemployment, retail and trade data obtained through the ABS officer to trade in foreign exchange derivatives.

Former NAB employee Lukas Kamay has been charged with insider trading. ( Supplied )

"In effect, he utilised sensitive ABS information to predict the fluctuations in the Australian dollar," AFP spokesman Ian McCartney said.

The two men attended Melbourne's Monash University together and police say it was during that time they struck up a friendship.

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Authorities will allege Kamay pocketed the majority of the $7 million windfall and will not specify how the pair communicated, although they say it was "regular" but "varied".

In an internal memo obtained by ABC's PM program, the ABS has told staff it is the first time ever that a staff member has been arrested for leaking data.

"Even though this is the first time in our history of more than 100 years that a staff member has been arrested for leaking statistics, it has the potential to tarnish our reputation as a trusted custodian of sensitive data," the memo said.

"We will undertake a thorough review to learn what we can from this incident. Fortunately, the police believe that no other ABS staff were involved."

Authorities say they began investigating after being alerted to "suspicious activity" on the foreign exchange market between August last year and May this year.

ASIC will not specify how it became aware of the transactions, but says there are a range of ways it can be alerted to insider trading, including complaints, tip-offs and surveillance.

The AFP obtained eight warrants to search the NAB in Melbourne and the ABS in Canberra as well as private homes in both cities.

They seized a property, a motor vehicle and funds totalling around $7 million.

Kamay faces court after 'complex investigation'

Kamay appeared in Melbourne Magistrates Court yesterday charged with insider trading, corruption of a public official, and money laundering.

Police say he was operating independently of his employer and did not use any of the bank's systems to carry out his alleged crimes. He has since been sacked from his job with the bank.

The 24-year-old ABS employee will be charged with insider trading, receiving a corrupt benefit, release of sensitive information and abuse of public office.

"This has been a complex investigation" Mr McCartney said.

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The NAB says it has terminated Kamay's employment while the ABS has suspended the 24-year-old worker, who it describes as "a relatively junior officer with trusted access" to information.

Chris Savundra from the corporate regulator ASIC says the Australian dollar is one of the most actively traded currencies on the global foreign exchange market.

"The alleged conduct has the potential to undermine confidence in the integrity of the foreign exchange market and disadvantage those that participate in the market without that inside information," he said.

"The foreign exchange market is a global, 24-hour decentralised market with average turnover of over $US5 trillion a day."

It is alleged the main data leaked from the ABS was labour force figures, showing unemployment and retail and trade information.

Evan Lucas, a market strategist with currency trader IG, says having such information ahead of time would give a significant advantage.

"Movements, particularly in things like Australian employment figures, also trade balance, are fairly influential in terms of how the Aussie dollar moves," Mr Lucas said.

"It has an effect for several reasons. Traders see it as basically a way of possibilities of movements in rate decisions from the RBA. They also see it in terms of the strength of the underlying economy.

"So if you've got employment figures that are better than expected it means the underlying economy is certainly on the up and therefore the Aussie dollar tends to move with that idea."

The AFP says both the NAB and ABS co-operated with their investigation.