US authorities are seeking the forfeiture of more than $US1 billion in seized Bitcoin it says are linked to the now-defunct criminal marketplace Silk Road.

Last week, the US Justice Department seized thousands of Bitcoin linked to Silk Road in the biggest cryptocurrency bust ever made.

Agents for the Internal Revenue Service Criminal Investigations Division recently identified more than 50 previously undetected Bitcoin trades that were executed through the Silk Road, the “most sophisticated and extensive criminal marketplace on the internet” which was shut down by US authorities in 2013, as reported by Bloomberg.

The Investigations Division recently identified more than 50 previously undetected Bitcoin trades that were executed through the Silk Road, the “most sophisticated and extensive criminal marketplace on the internet” which was shut down by US authorities in 2013.

These transactions were traced to a Bitcoin address, allowing authorities to zero in on the alleged hacker behind them, identified only as “Individual X”.

The address found is the world’s fourth richest Bitcoin address, according to BitInfoCharts.

“Criminal proceeds should not remain in the hands of the thieves,” Internal Revenue Service Criminal Investigation special agent-in-charge Kelly Jackson said.

“Through Criminal Investigation’s expertise in following the money, we were able to track down the illicit funds.

“The Washington DC Cyber Crimes Unit is uniquely specialised in tracing virtual currency transactions and we will continue to hone our skills to combat illegal activity.”

The US Justice Department is now seeking the forfeiture of these Bitcoins, which are currently worth more than $US1 billion.

“The successful prosecution of Silk Road’s founder in 2015 left open a billion-dollar question: ‘Where did the money go?’” US Attorney David Anderson said in a statement.

“Today’s forfeiture complaint answers this open question at least in part – $1 billion of these criminal proceeds are now in the United States’ possession.”

Silk Road was linked to murder-for-hire and drug sales, and was officially shut down in 2013, with its operator, Ross William Ulbricht, utilising Bitcoin to generate about $US1.2 billion in sales.

Silk Road took commissions worth $US80 million over its three years of existence.

Ulbricht was convicted by a New York federal jury in 2015 of seven criminal counts, including conspiracy to distribute narcotics and money laundering.

Crypto experts Chainanalysis said it assisted law enforcement track down the $US1 billion in Bitcoin, using its tools to weed out the cryptocurrency wallets associated with Silk Road. These Bitcoins accounted for nearly a fifth of the total activity of the cryptocurrency in 2013.

It comes amid a significant resurgence in the price of Bitcoin, skyrocketing by nearly 10 per cent to $US15,3000 recently, its highest point in two years.

The price of Bitcoin peaked at $US20,000 in late 2017 before tanking to $US3000 by the following year.

This recent surge has seen fintech giant Square put its support squarely behind the cryptocurrency, buying nearly 5,000 Bitcoins worth nearly $70 million, on the potential for Bitcoin to become the “ubiquitous currency”.

Australia also recently saw its own cryptocurrency controversy, with a former CSIRO worker pleading guilty to using the science organisation’s supercomputers to mine for cryptocurrency.

The individual received a 15-month sentence that will be served in the community through an intensive correction order.

It was found that they had mined $9,400 worth of cryptocurrencies using CSIRO’s supercomputers, with that time having cost CSIRO about $76,000.