By Peter Greste
East Africa correspondent, BBC News
Al-Shabab and its allies control most of southern and central Somalia
The Somali Islamist movement al-Shabab has banned the BBC and closed down transmitters broadcasting the Somali language service inside the country.
Al-Shabab accused the BBC of fighting against Islam and supporting the transitional federal government, which the rebels are fighting to overthrow.
The group said the BBC had been broadcasting the agenda of crusaders and colonialists against Muslims.
The BBC said it was strictly impartial and spoke to all sides in the conflict.
The BBC has been broadcasting its services in Somali, Arabic and English across the country on a series of FM frequencies for at least a decade, and surveys suggest it is one of the most widely listened-to news services in Somalia.
Al-Shabab ordered all of the BBC's transmitters to be shut down.
A statement by al-Shabab demanded that any organisation transmitting the BBC, or the Washington-based Voice of America, should cancel their contracts.
Al-Shabab and its allies control most of southern and central Somalia and all but a few districts of the capital, Mogadishu.
They have been fighting to establish an Islamist administration of their own in place of the current government.
The BBC's broadcasts have been taken off the FM bandwidth, but are still available on shortwave and the internet.
In response to the statement, the head of BBC Africa, Jerry Timmins, said the organisation spoke to all sides in the conflict, including al-Shabab, adhered to strict standards of impartiality and editorial independence and rejected any suggestion otherwise.