The BBC World News channel has been banned from buying certain programmes and accepting some sponsorship deals, after an investigation found serious breaches of the corporation's editorial guidelines in shows about subjects including Malaysia and carbon trading.

A full investigation was launched by the BBC Trust into programming on BBC World News, a commercial channel distributed internationally, after it found conflict of interest and sponsorship issues with a show called Taking the Credit, about carbon trading, originally broadcast in 2009.

The investigation by the trust's editorial standards committee (ESC) found a further 15 programmes broadcast on the channel in serious breach of the BBC's editorial or sponsorship guidelines.

These programmes included eight containing sections about Malaysia made by a company called FBC Media, which had an "apparent financial relationship" with the Malaysian government.

FBC Media's parent company, FBC Group, confirmed to the BBC investigation that the Malaysian government was a client.

"Based on evidence before the committee of the apparent financial relationship between FBC Media (UK) Ltd and the Malaysian government, the committee concluded that FBC Media (UK) Ltd was not an appropriate producer for these particular programmes, being about Malaysia, its industries and Malaysian government policies," the ESC concluded.

"The committee considered that it could not be adequately confident that a relationship between FBC Media (UK) Ltd and the Malaysian government and/or other Malaysian interests had not affected the content of BBC output.

"In light of the overall content covering Malaysia, the committee was concerned that the BBC has broadcast programmes which may have promoted particular subject matters (or presented them in a certain way) as a result of a production company's financial interests."

All 15 programmes were found to have been in breach of one, or more, of the BBC's rules governing conflicts of interest, promotion of a sponsor's activities and sponsorship of current affairs shows.

The shows had been bought by the BBC for a "low or nominal cost" from independent producers.

"International audiences must be able to rely on the same integrity and independence in the BBC's editorial decisions as audiences in the UK," said ESC chair Richard Ayre. "We have found that several programmes shown on the BBC's World News channel had been inappropriately sponsored. The trust is deeply concerned at this and we very much regret that these programmes failed to live up to the editorial standards we set for the BBC."

As a result of the investigation the BBC World News channel has been banned from buying programmes for a low or nominal cost and it will "no longer accept sponsorship from non-commercial organisations".

In May, the BBC Trust found Taking the Credit in breach of editorial guidelines around sponsorship of a current affairs show and conflict of interest.

Taking the Credit was funded by a company called the Africa Carbon Livelihood Trust, which had links to a firm called Envirotrade, which featured in the documentary.

According to the BBC Trust, the ESC "concluded that the funding in full or in part of this programme by Envirotrade – via the Africa Carbon Livelihoods Trust – amounted to sponsorship".

"However, the committee considered that the programme was current affairs and that such sponsorship was in breach of the guidelines, which prohibit any sponsorship of news and current affairs," the trust said.

According to the BBC Trust there was a conflict of interest because "there was an inextricable link between the funder organisation and a project featured in the programme".

"Further, the programme portrayed the work of Envirotrade in a positive way and as a result breached the requirement that sponsors' activities should not be promoted. The programme also failed to credit the sponsor in the programme, so the viewers were unaware that there was a funding arrangement in place."

A BBC World News spokesperson said: "We accept the BBC Trust's findings. We are committed to the highest standards of broadcasting and our editorial independence must always remain protected.

"There were breaches of BBC guidelines though we note that the trust report found no breaches of impartiality in any of the programmes. We are determined to learn any lessons from this process. That is why we have set out a robust action plan which has been endorsed by the ESC.

"We are now committed to bringing in a series of changes to tighten our systems and strengthen the protection of our editorial independence."

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