Reports say US authorities are looking at misconduct and fraudulent trading behavior around crypto-currencies.

US legal authorities have launched a criminal probe into whether traders have been manipulating Bitcoin and other crypto-currency prices, adding to controversy about a technology area people claim is dangerously opaque, Bloomberg reported, citing unnamed sources.

The US Department of Justice is examining practices that can move prices, such as making fake orders to trick other traders into buying or selling - the kind of misconduct seen in other markets down the years. Federal prosecutors are working with the Commodity Trading Commission, which oversees derivatives tied to Bitcoin.

The newswire report follows that of the Wall Street Journal, which on May 17 found that hundreds of technology firms raising money are using deceptive or even fraudulent tactics to lure investors. In a review of documents produced for 1,450 digital coin offerings, the WSJ said it found 271 with red flags that include plagiarized investor documents, promises of guaranteed returns and missing or fake executive teams.

Bitcoin, the best known of the crypto-currencies, surged last year in an extraordinary rally, but has come down to earth spectacularly, albeit off its lows.

Central banks, legal bodies and governments worry that crypto-currencies are conduits for dirty money, cyber-criminals and even terrorists. Central bankers also, arguably, are concerned that if such apolitical cash catches on in a big way, it will make it harder to effectively guide economies via interest rates. Crypto-currency defenders argue that that is the whole benefit of such currencies in that they limit the ability of governments to debase fiat currencies such as the dollar, euro or Swiss franc.

The article on the US probe said the illicit tactics being investigated include spoofing and wash trading. In spoofing, a trader submits a spate of orders and then cancels them once prices move in a desired direction. Wash trades involve a cheater trading with herself to give a false impression of market demand that lures other to also participate.

It said a Justice Department spokesperson declined to comment and CFTC officials didn’t respond to requests for comment.