A police investigation could be carried out after a Sheffield radio station broadcast a hate cleric's sermons 'encouraging and condoning' violence towards non-Muslims.
The station has been taken off the air following the broadcast of pre-recorded lectures by American Muslim cleric Anwar al-Awlaki, which were found on the internet and used to fill the airwaves during the holy month when the station was without its regular presenter.
Regulator Ofcom said that parts of al-Awlaki's lectures amounted to a 'direct call to action to members of the Muslim community to prepare for and carry out violent action against non-Muslim people'.
Ofcom also said it has 'serious concerns' about Iman FM's decision to give a platform to a 'widely-known terrorist leader and al-Qaeda recruiter'.
Al-Awlaki was declared a global terrorist by the US government in 2010. His sermons are believed to have inspired several recruits to Islamic militancy.
He was killed in a drone strike in Yemen, authorised by President Obama, but his writings and sermons remain available online.
Iman FM said the lectures were broadcast 'unwittingly'.
A South Yorkshire Police spokeswoman said: "We are working closely with Ofcom as they continue their thorough investigation into this matter, to determine whether any criminal activity has taken place.