International security forces have brought down two big dark web marketplaces.

The US Justice Department has shut down AlphaBay, while law enforcement in the Netherlands has taken down Hansa Market.

Both sites were alleged to have traded drugs, firearms, computer hacking tools and other illicit goods.

US authorities say it was one of the largest law enforcement actions ever taken on the dark web, where users access secretive sites using layers of encryption and data-scrambling.

AlphaBay was several times larger than it predecessor Silk Road, which was shut down in 2013.

“The dark net is not a place to hide,” US Attorney-General Jeff Sessions said.

“This is likely one of the most important criminal investigations of the year – taking down the largest dark net marketplace in history.”

But just like when governments try to take down pirate video sites, new versions are expected to pop up.

“The takedown of AlphaBay is significant, but it's a bit of a whac-a-mole,” said Frank Cilluffo, director of the Centre for Cyber and Homeland Security at George Washington University.

AlphaBay and Hansa Market were two of the top three dark web marketplaces, Europol chief Rob Wainwright said.

He said the international effort to seize the AlphaBay servers involved authorities in Thailand, Lithuania, Canada, Britain and France.

AlphaBay founder Alexandre Cazes was a Canadian citizen, but was arrested on behalf of the United States in Thailand.

Reports say Mr Cazes was logged on to AlphaBay at the time of his arrest, so that authorities could access his accounts and other information about the site's servers.

Mr Cazes apparently took his own life a week later while still in Thai custody, facing charges relating to narcotics distribution, identity theft, money laundering and other crimes.