A London university that was found to have serious problems with campus radicalisation has won praise from extremism monitor Quilliam after withholding campus space for Muslim prayers unless staff are permitted to oversee the content of sermons.

Three years ago, Quilliam found evidence that City University's Islamic society was promoting a "hard-line Islamist ideology", with its president calling for kaffirs (unbelievers) to be killed and for adulterers to be stoned, and creating an environment that "scared" Jewish students and moderate Muslims.

The research looked into a period in 2010 when City University students mounted street protests over the replacement of a Muslim-only prayer room with a "multi-faith" facility. A fresh controversy has now erupted over the university's decision to stop offering space on City premises for Friday prayers because "despite repeated requests and assurances" for organisers to "work with the university's Imam to ensure that the process for selecting students is transparent and that the content of sermons is made known to the university in advance… the information from those students leading Friday prayers was not forthcoming.

"The university could not continue to condone an activity taking place on its premises where it cannot exercise reasonable supervision," said a City spokesman, adding that the university had identified nearby locations off campus at which students could attend prayers.

According to the group Muslim Voices on Campus, which has enlisted lawyer and Cageprisoners spokesman Saghir Hussain to help challenge the decision and has won support from the students union's vice president of activities, the issue is one of free speech. "When you start submitting your sermons to be monitored and scrutinised then there's a chance for it to be dictated what's allowed and what's not allowed," said Wasif Sheikh, the group's leader.

But Usama Hasan, senior researcher at Quilliam, said this was disingenuous and that extremism at City was still a serious concern. "It hasn't got rid of its problems," he said.

"They are pretending there is no past history [of radicalism] at City," he said. "We know what happened there. The university cannot afford that situation again - they need to keep out the hardliners. They are doing the right thing."

Although the Friday prayers are not specifically run by the ISoc, the ISoc has launched a "freedom of faith" campaign urging the university to reconsider. Mr Hasan said there was evidence of "clear continuity" between those involved in the 2010 protests and the campaign today.

The campaign also has the backing of the Federation of Student Islamic Societies, which has a record of inviting extremist speakers on to British campuses and in 2011 was labelled "an umbrella organisation which has failed to challenge sufficiently terrorist and extremist ideologies" by Nick Clegg.

City Jsoc's Rachel Blain said that they supported the doctrine of freedom of religion, including prayer, and believed that City should allocate space for Muslim prayer to go ahead.

"If Jsoc wanted to hold a minyan at City we would expect to be granted the right to do so," she said. "However, we also understand the guidelines laid down by the university and believe the Isoc has a responsibility to provide copies of their sermons.

"In light of the extremism on campus in 2010 we believe the university has an obligation to fulfil their responsibility in overseeing all events in order to prevent extremism on campus in the future."

The president of City's student's union, Giulio Folino, said that the university should not interfere with freedom of speech, but that "the university needs to be reassured of the appropriateness of discussions on university property".