Cloud storage startup Dropbox has raised an additional $350 million in a Series C round at a valuation of $10 billion, TechCrunch reported citing a regulatory filing and a source who has knowledge about the funding. According to the TechCrunch source, the company's existing investors and major mutual funds contributed to the round.

A report in The Wall Street Journal last month said the cloud storage firm secured an additional $250 million at a valuation of $10 billion. The figure was revised to $350 million by The WSJ in a February 13 report, also at a $10 billion valuation. Citing a source familiar with the fundraising, The WSJ said the backers for that round were BlackRock, T. Rowe Price and Morgan Stanley Investment Management. These reports were never confirmed by Dropbox itself, the TechCrunch report said.

The filing submitted to the US Securities and Exchange Commission revealed that the round could reach as much as $450 million and to date, the company has already secured $325 million. At this rate, $350 million would be the likely target since this is also the same amount that another news outlet, Fortune, has also heard of, the report said.

According to the February 13 WSJ report, Vice President Sujay Jaswa said in an earlier interview that the funds will help grow the startup's workforce which is set to increase to 1,000 in 2014. He added that Dropbox is looking to open at least one office in Asia this year, the report said.

The WSJ report said Dropbox could also use the funds for deals that could increase its user base. It cited the 2011 agreement the company had with Samsung which placed the Dropbox software on the South Korea-based firm's premium Android phones. Although it was initially expensive for the startup at first, it did bring in more mobile customers to its platform, The WSJ reported.