A British radio station that broadcasts content for Muslims risks being closed down after transmitting 25 hours of sermons from the Al-Qaeda preacher Anwar Al-Awlaki.

Britain’s radio regulatory authority Ofcom suspended Sheffield-based Iman FM’s broadcasting license after receiving complaints about the transmissions, which the watchdog said “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.”

The managers of Iman FM deny that they intentionally broadcast lectures by Al-Awlaki – who was killed in a US drone strike in 2011 — calling for a holy war.

The lectures were broadcast on June 14 in English. In one, Al-Awlaki states: “Prepare whatever strength you have for holy war in the cause of Allah. This is a form of worship.”

Under British broadcasting rules hate speech is not permitted on television or radio programs, unless it is in context.

It is well documented that Al-Awlaki was an American Muslim cleric of Yemeni descent, and an Al-Qaeda leader, recruiter and trainer.

It is widely reported that Al-Awlaki inspired the Charlie Hebdo attack in Paris, plans to blow up a US passenger jet, and the Fort Hood massacre in Texas, that left 13 dead.

The station’s managers say they found the content on YouTube and broadcast it during Ramadan, but said they did not know the precise content of the lectures. Ofcom dismissed the station’s claims, saying their explanation was “not credible.”

The management at Iman FM have been given 21 days to explain their actions, or risk the permanent closure of the station.

Iman FM’s chief executive, Mohammad Mughal, said: “This is very, very sad because none of us had any idea this lecture was preaching hatred… We are not just a Muslim radio station — we regularly feature Christian presenters.”