Two of the largest TV networks in the US have teamed up to offer a new online video service that will feed content to some of the most popular sites on the internet.

News Corp and NBC announced a joint online video venture which will offer clips and full-length episodes of Fox and NBC TV shows. 

The service will not focus on distributing video from a central site, but will deliver content through a network of already-popular web portals. Yahoo, MSN and MySpace will be among the first sites to offer the videos. 

Shows lined up for the new service include The Simpsons, Saturday Night Live, 24, and The Tonight Show.

The companies hope that the service will catch on with users and at the same time prevent any legal issues over the content's copyrights.

YouTube especially has been struggling to filter out copyrighted material posted without the owners' permission.

"Anyone who believes in the value of ubiquitous distribution will find this announcement incredibly exciting," said Jeff Zucker, president and chief executive of NBC Universal.

"This venture supercharges our distribution of protected, quality content to fans everywhere.

"Consumers get a hugely attractive aggregation of a wide range of content, and marketers get a novel way to connect with a large and highly engaged audience."

Analysts, however, have suggested that the proposed 'YouTube killer' will be anything but.

"It will not challenge YouTube, which is two parts social experience, one part video experience. That's how it gets millions of viewers," Forrester Research vice president James McQuivey said on a company blog. 

"But this site could draw traffic from NBC.com or Fox.com, as viewers learn to seek the show they like rather than the network that produces it. If other networks come on board it could become a significant online destination."

Networks have expressed growing frustration at the inability of YouTube and parent company Google to keep pirated videos off of the site. 

Negotiations for a rival video site that included Fox and NBC TV shows were said to be in the works as far back as December of last year. YouTube meanwhile has signed content distribution deals with the BBC and Warner Music.