Megaupload boss Kim Dotcom has revived plans to launch a new online music venture this year and hinted at the return of the file-sharing site that led him to face online piracy charges.

Dotcom's original plans for the music service, called Megabox, were disrupted in January when New Zealand police raided his Auckland mansion and arrested him as part of a major US investigation into alleged copyright theft.

The 38-year old, who is free on bail, took to Twitter this week to say that Megabox was back on the drawing board and would launch in 2012.

"Yes... Megabox is also coming this year," he told his 110,000 followers on the micro-blogging site.

In an earlier tweet this week, he said: "I know what you are all waiting for. It's coming. This year. Promise. Bigger. Better. Faster. 100% Safe & Unstoppable."

It was unclear whether this tweet referred to new Megabox service or Megaupload, the file-sharing site was the cornerstone of his Internet empire before it was shut down as part of the US investigation.

The German national, who has refused interview requests saying he wants to keep a low profile, was not available for comment but tweeted last month: "Mega will return and it will be UNSTOPPABLE!"

Dotcom did not reveal a specific launch date or details of how the planned Megabox music service would work.

He told technology website torrentfreak.com last December that Megabox would allow artists to keep 90 percent of earnings from their songs by letting them sell directly to consumers, bypassing record labels.

Dotcom is due to face a court hearing in March next year which will determine if US authorities can extradite him and three co-accused on charges of money laundering, racketeering, fraud and online copyright theft.

He faces up to 20 years jail if convicted in a US court.

Dotcom, who changed his name from Kim Schmitz, has denied the charges and tweeted as recently as Tuesday that he was not guilty.

The FBI and US Justice Department allege Megaupload sites netted more than $175 million in criminal proceeds and cost copyright owners more than $500 million by offering pirated copies of movies, TV shows and other content.

Dotcom was initially denied Internet access when granted bail in New Zealand but successfully appealed for the right to go online, arguing it was necessary to organise his defence.

No bail conditions limiting his online activities or preventing him from launching new Internet ventures were imposed, although any Megaupload reboot is likely to have stringent copyright protections to prevent further legal issues.

In recent months, his public Internet presence has chiefly focused on rallying support for his cause, including a website kim.com and an online song accusing US President Barack Obama of waging war on cyber-freedoms.