Officials in the US have opened a criminal investigation into whether traders are manipulating the price of Bitcoin and other digital currencies.

The Justice Department is said to be looking into techniques used to bump up prices including spoofing, in which traders flood the market with fake orders that are never fulfilled and wash trading, which gives a false impression of market demand when a buyer purchases against themselves, tempting others to follow suit.

Prosecutors are working with the Commodity Futures Trading Commission, a financial regulator that oversees trading against cryptocurrencies, according to Bloomberg.

The crackdown comes amid growing concerns that hugely popular virtual currencies are particularly susceptible to fraud and claims that exchanges, the websites where people can buy and sell currency, are encouraging cheating. Meanwhile, alarming swings in value, a lack of regulation and a growing trend in dubious celebrity-backed "initial coin offerings" have raised alarm bells across the world, forcing China to ban cryptocurrency trading and Japan and the Philippines to bring in regulators.

Bitcoin has enjoyed a meteoric rise, surging to almost $20,000 toward the end of 2017 after starting the year below $1,000. But potential regulation in the US and the UK has dampened traders' spirits, with a slump in value to $7,500 on Thursday.