A suspect in the Boston Marathon bombings subscribed to a YouTube channel run by a former Highgate School pupil – featuring sermons from controversial groups and figures – just weeks before he allegedly launched the deadly attacks.

Tamerlan Tsarnaev, the elder of two brothers suspected of the bombings, signed up to online channel Allah is the One – run by an organisation called the Merciful Servant, which is administered by 26-year-old former Highgate School pupil Hasan Sarwar.

The channel features a video which brands gays “sodomites” in a clip apparently supporting the belief that Muslim men should be allowed up to four wives.

The channel, set up in 2010, also has footage of radical preacher Zakir Naik, who was banned from Britain by home secretary Theresa May after backing Osama Bin Laden and saying “every Muslim should be a terrorist”.

Clips of Hamza Tzortzis, from the Islamic Education and Research Academy – a group banned from University College London after separating men and women at an on-campus debate – also feature on the channel.

Mr Sarwar, a student at the top independent school in Highgate from 1994 to 2004, said: “We have got many subscribers – Muslims and non-Muslims. Our message is the peace and mercy of Islam.”

He confirmed he had not known that Tsarnaev had signed up to the channel two months before he allegedly planted bombs near the finish of the Boston Marathon.

The channel posted a new video aftering the bombings entitled Dear Boston From London which says “killings of non Muslims and Muslims is completely wrong”.

Last week the channel changed its logo from a masked mujahideen fighter to a dove-like image.

Tsarnaev is thought to have become radicalised after watching online sermons by extremist clerics before allegedly planting bombs at the Boston Marathon last week with his younger brother Dzhokhar, 19.

According to his profile on social networking website LinkedIn, Mr Sarwar took his GCSEs and A-levels at Highgate School, where he was a member of the Economics Society, before studying economics and management at Queen Mary, University of London.

The 26-year-old, of Drayton Park, Highbury, was a fundraising and event manager at Haringey Council from 2003 to 2005 and is now a senior partner at Clerkenwell-based Fur Elise Media.

Preacher Zakir Naik, Hamza Tzortzis and the north west-London-based Islamic Education and Research Academy have publicly insisted they condemn violence.