Preachers give talks and respond to questions from users of chat site in event advertised on Twitter a fortnight ago

Three previously jailed hate preachers have hosted an online conference for scores of Islamist radicals to give their backing to the newly established Islamic State (Isis).

More than 200 people joined the conference on Saturday night to hear preachers who between them have served over 10 years in prison for soliciting murder and stirring up racial hatred.

The former independent reviewer of terrorism legislation Lord Carlile said the conference demonstrated the need for a new globally enforced pact to deal with online radicalisation occurring across several countries.

"We have to recognise that electronic media means that borders can not prevent conversation and heretical preaching," Carlile said. "I think the next stage for governments is to ensure that this kind of chatroom is properly policed on the internet."

During the stream, hosted on the video chat site Paltalk, radical preachers claimed that democracy was leading people astray, that the Islamic State head Abu Bakr al-Baghdadi was the leader of all Muslims, and that homosexuals were "the greatest threat to our existence".

Openly advertised on Twitter more than a fortnight ago, the talk continued into the early hours of Sunday morning with listeners from the UK and beyond posting questions for the speakers.

One of the speakers, Atillah Ahmed, who uses the name Abu Abdullah, is a former football coach from Bromley, south London, and a former associate of Abu Hamza. In 2008 he was sentenced to almost seven years in prison after pleading guilty to solicitation of murder.

He told online attendees that although western Muslims may not be the most knowledgeable about their religion, they made excellent fighters according to Syrians on the ground. "You will not see bigger, stronger lions on the battlefield than these brothers," he said.

"What about ourselves sitting on our backsides eating cakes and biscuits at home while they're [the fighters of Islamic State] struggling to bring honour to the community of Islam?" he asked.

Speaking in a thick south London accent, Ahmed described democracy as an evil system and condemned imams who pledged support for democratic values as "imposters".

In a tract against homosexuality, he said: "Now we see rampantly these infidels in democracy passing laws that it's OK for a man to marry a man. These people [homosexuals] are the greatest threat to our existence."

Another speaker, Abdullah el-Faisal, a one-time imam of Brixton mosque, was jailed for four years in 2003 and is said to have played a part in radicalising the shoe bomber Richard Reid and the 7/7 bomber Jermaine Lindsay.

Faisal started his talk by thanking his "brothers from al-Muhajiroun", a group proscribed under UK law. "The reason we … like our brothers in al-Muhajiroun is because … they believe in sharia [Islamic law], Khilaafa [the Caliphate] and jihad," he said.

During his 45-minute talk delivered from Jamaica, Faisal condemned others for not supporting Isis. "Instead of embracing the Islamic State, supporting the Islamic State and doing everything humanly possible for the success of the state … all they do is slander the mujahideen," he said.

He described women captured by Isis soldiers during the conflict as the "spoils of war".

A third speaker, Mizanur Rahman, who is in his early 30s, was convicted of hate speech and solicitation to murder following protests over Danish cartoons in 2006.

He said he was speaking in front of a "hall full of Muslims" who were listening to the conference. They could be heard laughing when Rahman, who used the moniker Ab Baraa, was asked by chatroom members about the best way to travel to Syria and Iraq to join Isis. "Ask your local Thomas Cook. God willing they can find you a five-star hotel as well," he said.

Carlile said new global legislation akin to that drawn up after 9/11 was needed to ensure that jurisdictional issues did not get in the way of proper policing of the internet. "It's not rocket science to find out what people are doing on these conference sites so plainly the next stage is legislation, otherwise we give them a free run," he said.