Almost half a million users were using the website DarkMarket to sell drugs, counterfeit cash, stolen credit card data, anonymous SIM cards and malware.

It was allegedly being run from servers in Germany by a 34-year-old Australian, who was arrested on the German-Danish border on January 11.

Following a German tip-off, Australian Federal Police officers raided properties in Park Ridge, Mount Cotton and Molindar and seized a laptop, four mobile phones, USB thumb drives and hard drives on Wednesday and Thursday.

Police are considering arrests and are investigating whether drugs and contraband were sold on DarkMarket in Australia.

"Some of these items could have been used or acquired by Australians in Australia. The job of the AFP and its partner agencies is to keep Australians safe,'' AFP Acting Commander Jayne Crossling said in a statement on Sunday.

"If police knew there was criminal activity occurring in geographic location, action would be taken.

"There is no difference with the dark web, although the anonymising features of the dark web makes it harder for law enforcement to identify perpetrators, who commit abhorrent crimes."

The AFP said there were more than 2400 sellers and more than 320,000 transactions occurring on DarkMarket before German police brought it down.

Almost $220 million worth of cryptocurrency was being traded on the website.

Ms Crossling said dark web marketplaces were commonly used by human traffickers and organised crime syndicates.

She said a Canberra woman was arrested in December for allegedly contracting the killing of her parents over the dark web.

"The AFP works very effectively with law enforcement globally to combine tools and expertise to reduce the risk of harm to the community. Despite that, too many crimes are being facilitated on the dark web," Ms Crossling said.

Australian Associated Press