A former blogger for a US mobile phone news site is being sued by his erstwhile employer over ownership of his Twitter feed in a social media test case for the Internet age.

Noah Kravitz, of Oakland, California, worked as a product reviewer and video blogger for South Carolina-based PhoneDog from 2006 to 2010, according to the lawsuit filed in the US District Court for Northern California.

While working for PhoneDog, Kravitz attracted 17,000 followers to his Twitter account @PhoneDog_Noah, according to the suit, which was filed in July but has attracted media attention following an article about it in The New York Times.

The suit alleges that when Kravitz "suddenly resigned" in October 2010 he was asked by PhoneDog to relinquish the account but he declined to do so and "merely changed" his Twitter handle to @noahkravitz.

The suit claims that Kravitz now works for a rival company, TechnoBuffalo, and is using his Twitter account to "discredit PhoneDog."

PhoneDog is seeking damages from Kravitz of $340,000 based on a value of $2.50 per Twitter follower, or $42,500 a month for the past eight months.

Kravitz told The New York Times that he had left PhoneDog on good terms with an agreement that he would "tweet on their behalf from time to time."

Eight months later, however, the company filed suit against him, a move Kravitz told the newspaper was retaliation for his claim to 15 percent of PhoneDog's gross advertising revenue.

In a statement to the Times, the company said: "The costs and resources invested by PhoneDog Media into growing its followers, fans and general brand awareness through social media are substantial and are considered property of PhoneDog Media.

"We intend to aggressively protect our customer lists and confidential information, intellectual property, trademark and brands," it said.

Henry Cittone, an intellectual property lawyer, told the Times the case will "establish precedent in the online world, as it relates to ownership of social media accounts.

"We've actually been waiting to see such a case as many of our clients are concerned about the ownership of social media accounts vis-a-vis their branding," Cittone said.