Iranian news channel Press TV disappeared from British television screens on Friday after Britain's independent media regulator revoked its licence in a move likely to fan diplomatic tensions with the Islamic Republic.
Press TV said the move was politically motivated but regulator Ofcom denied it was acting at the British government's behest and said the broadcaster had broken licensing rules.
Britain has been a focus of Iranian ire over steps to tighten sanctions over Iran's disputed nuclear programme.
Britain shut Iran's embassy in London and expelled all its staff in November after its embassy in the Iranian capital Tehran was overrun by a crowd angry at British sanctions.
Ofcom said its decision was based on Press TV's failure to declare that Tehran rather than London was its editorial base when it was granted the licence.
Press TV is a 24-hour news channel owned by Iran's state, available via satellite around the world and on the Internet.
Its English-language service was removed from Sky TV's satellite platform on Friday as a result of the decision. It will still be available online.
Britain's Foreign Office said it was not involved in the decision but had been concerned about allegations that Press TV had broadcast forced confessions from detainees.
Press TV said on its website the move was "a clear example of censorship".
The story led Press TV's news bulletins where its reporter said the move appeared politically motivated, aimed at silencing a broadcaster that had focused in part on the failings of British domestic and foreign policy.
"Ofcom cannot claim that it is not a part of the British government ... and it acts exactly in line with the policies of the British government. Otherwise, it would not be possible to prevent an international network and an alternative voice in Britain (from broadcasting)," Press TV's newsroom director Hamidreza Emadi told state television.
"This action has not been successful in stopping the activities of Press TV. We have tested and come up with several ways to broadcast our programmes for our viewers," he added.
George Galloway, a former member of the British parliament who hosts a talk show on the channel, called Press TV a "voice for the voiceless ... This is a blow for Press TV ... but it is more of a blow to the British government's hypocritical stance of being in favour of freedom of expression," he said.
Ofcom, which is accountable to parliament, rejected the claim it was acting on behalf of the British government. "Ofcom's decisions are made independently in accordance with its statutory powers and duties under the Communications Act 2003," a spokeswoman for the regulator said.
The roots of the Ofcom decision lie in a ruling last month to fine Press TV 100,000 pounds ($155,000) for broadcasting an unauthorised interview with an imprisoned Newsweek journalist.
Ofcom said it emerged during that case that editorial control of Press TV was exercised from Tehran rather than London and the broadcaster had failed to amend its licence accordingly.
Press TV was given a licence on the basis it was run out of London. Foreign media groups can hold UK broadcast licences but must be open about where editorial control is based.
Ofcom also said Press TV Limited had not paid the 100,000-pound fine and it would pursue that matter separately.
"We have been concerned for some time by serious allegations about Press TV, in particular that it has been involved in broadcasting confessions obtained under duress," the Foreign Office said.
"It is right and proper that these allegations should have been investigated by Ofcom, as the independent regulator of the UK media. Ofcom is independent of the government. The government was not involved in this decision."