US authorities have arrested two people and seized $3.6 billion wort of bitcoin in relation to the 2016 hack of cryptocurrency exchange Bitfinex.

Ilya Lichtenstein and his wife Heather Morgan were arrested on Tuesday for an alleged conspiracy to launder the proceeds of 119,754 bitcoin that were stolen from Bitfinex’s platform after a hacker breached the exchange's systems.

The hack saw more than 2000 unauthorised transactions which sent the stolen bitcoin to a digital wallet controlled by Lichtenstein, say authorities.

According to the Department of Justice, over the last five years, about 25,000 of the bitcoin were move from the wallet via a "complicated money laundering process" that ended with some of the funds being deposited into financial accounts controlled by Lichtenstein and Morgan.

Deputy Attorney General Lisa O Monaco says: “Today’s arrests, and the department’s largest financial seizure ever, show that cryptocurrency is not a safe haven for criminals.

“In a futile effort to maintain digital anonymity, the defendants laundered stolen funds through a labyrinth of cryptocurrency transactions. Thanks to the meticulous work of law enforcement, the department once again showed how it can and will follow the money, no matter what form it takes.”

Lichtenstein and Morgan both face charges of conspiracy to commit money laundering and conspiracy to defraud the United States. If convicted they could face up to 20 years in prison for the first charge and five years for the second.