A campaign advert made by a organisation founded by U2 singer Bono has been banned from UK TV because it may breach political advertising rules.
The short film is part of One's Hungry No More campaign which calls for governments to help tackle the causes of famine in Africa.
Clearcast, which approves adverts, said it could be in breach of rules laid down by the 2003 Communications Act.
One said it was "absurd" the advert could not be shown.
The minute-long film, called The F Word: Famine is the Real Obscenity, features stars including Bono, George Clooney, Colin Farrell and Sex and the City star Kristin Davis.
A Clearcast spokeswoman said: "These rules ensure that adverts aren't being broadcast by bodies whose objects are wholly or mainly political.
"One appears to be caught by this rule as they state that part of their raison d'etre is to pressure political leaders.
"It also appears that a number of the claims made in the version of the ad that we have seen are directed towards a political end, which is again against the rules."'
However Adrian Lovett, Europe director of One said the organisation was not a political party and had no political affiliation.
"We recognise the purpose of the broadcasting code is to keep political propaganda off British television," he said.
"But our ad highlights the desperate plight of 750,000 people in east Africa who, the UN warns, could die before the end of the year.
"Unless we keep the spotlight on this crisis and the need for urgent action, those people will be forgotten. Who can object to that message? We are challenging this decision and hope the broadcasters will reconsider."
Clearcast said that a broadcaster carrying an advert in breach of the rules on political advertising faces a possible fine from broadcasting watchdog Ofcom or even a revocation of its licence.