The BBC has ordered "urgent inquiries" into how its news coverage is being apparently censored when broadcast abroad, with scenes about anti-government protests removed.
The development is serious for the BBC because it risks undermining its global reputation for impartiality.
The censorship accusations are especially embarrassing for the Corporation as it comes as the broadcast regulator Ofcom is investigating a "news fixing" scandal involving BBC World News and other global broadcasters, revealed in The Independent last year.
Viewers in Malaysia thought they were watching a BBC World News package on violent anti-government protests last Saturday. In fact, the original report made by BBC correspondent Emily Buchanan had been heavily re-edited by a local satellite broadcaster which carries the BBC channel.
The censorship was exposed in a YouTube clip which juxtaposed the full report, introduced by presenter Dani Sinha and shown elsewhere on BBC World News, with the version shown in Malaysia. By last night hundreds of thousands of viewers had seen how several controversial parts of the film had been cut, including shots of police firing water cannon, a protester claiming officers had opened fire on the demonstration and a man claiming elections in Malaysia were neither independent nor clean.
The edited report was shown by Astro, the direct broadcast satellite service which carries BBC World News in Malaysia. In recent days police have fired tear gas at tens of thousands of protesters involved in electoral reform demonstrations in the Malaysian capital Kuala Lumpur.
In a statement, the BBC expressed its concerns at the apparent censorship: "The BBC is making urgent inquiries to the Malaysian operator, Astro, to establish the facts."
A BBC spokesman said. "During the week of World Press Freedom Day, it would be deplorable if access to independent and impartial news was being prevented in any way. We would strongly condemn any blocking of the trusted news that we broadcast around the world, including via distribution partners."
Clare Rewcastle of the Sarawak Report said she had set up her campaigning website because of censorship in Malaysia, where the same regime has been in power for more than half a century.
"The press and broadcast media in Malaysia is completely controlled and manipulated by the regime and there is no access to unbiased reporting except on the internet," she said.
"Clearly in this case there was a similar attempt to introduce bias into an objective BBC report that related to police brutality against peaceful demonstrators. It shows the regime in its true colours, but if this sort of doctoring of BBC reports is permitted on the part of regimes like Malaysia, then it puts the integrity of the BBC at a severe reputational risk."
Al Jazeera also complained that coverage of the protests by its correspondent had been doctored by the satellite service.
Astro said it had a right to edit international channels so they complied with content regulations. The company said it was "surprised and somewhat disappointed" by the BBC's reaction.