The 38 million subscribers to MySpace, which News Corp bought for $629m (£355m) last July, discovered that when they wrote to each other about rival video-swapping site YouTube, the words were automatically deleted, and attempts to download video images from YouTube led to blank screens.

The intervention by News Corp in the traditionally open-access world of the web - in particular the alteration of personal user profiles - provoked a storm of angry posts in online "blogs".

"This is soooo like Fox and News Corp to try and secretly seal our mouths with duct tape," wrote "Alex" to Blog Herald.

The protests gathered pace, and when 600 MySpace customers complained and a campaign began to boycott the site and relocate to rival sites such as Friendster, Linkedin, revver.com and Facebook.com, News Corp relented and restored the links.

However, MySpace managers promptly shut down the blog forum on which members had complained about the interference. An online notice said the problem was the result of "a simple misunderstanding".

The explanation did not, however, calm the bloggers. "There was an outcry by some members after MySpace's acquisition by News Corp. People were afraid they might start monitoring or censoring MySpace," Ellis Yu wrote to the Blog Herald. "At the time, their CEO said nothing like that would happen. Well, now it has. MySpace was built on an open community and now they're trying to censor us, putting business interests above its members!"

"MySpace is supposed to be a personal forum!" wrote "makisha" at the blog site Supr.c.iliu.us. "Now it's owned by some corporation and it's being sensored [sic]! The beauty of it has been ruined. Better wise up MySpace or you're going to loose [sic] a good portion of your subscribers."

A spokesman for MySpace said it would not explain how the blocking of YouTube came about, nor how it was resolved, nor whether in future it would continue to block links to rival websites or censor messages between MySpace customers.

Mr Murdoch, 74, last week appointed 33-year-old Jeremy Philips to run News Corp's internet strategy and armed him with a $1bn fund to buy more sites.