WASHINGTON (AFP) - - The two founders of Skype are seeking to buy back the hugely popular Internet telephone service that they sold to online auction giant eBay in 2005, according to US media reports.

Niklas Zennstrom, from Sweden, and Janus Friis, from Denmark, founded Skype in 2003 and sold it to eBay two years later for 2.6 billion dollars.

They are now seeking to raise one billion dollars from private equity firms to re-claim their brainchild, the New York Times reported Friday, citing several people familiar to the matter.

eBay would be looking to sell the phone service for at least 1.7 billion dollars, the daily reported.

Since its sale the number of Skype users has exploded from 53 million registered users to 405 million users, yet the voice and text company's business model remains modest -- as it relies on mostly free user-to-user calls, its revenue in the 2008 fourth quarter was 145 million dollars.

The auction house's chief executive, John Donahoe, has "repeatedly signaled his willingness to sell Skype for the right price," the Times said, noting that it was unclear whether there have been direct negotiations between the parties.

In recent weeks Skype enabled Apple iPhone owners to use its service through a free software application.

Skype, which has its headquarters in Luxembourg, bypasses the standard telephone network by channeling calls over the Internet.

Its service features include being able to call other users free of charge and the ability to connect with land lines or mobile devices at low rates.