LONDON, Britain: Tens of thousands of mourning people gathered in central London to protest against the deadliest attack on the holy shrine of holy Prophet Hazrat Muhammad Al-Mostafa (p)’s 10th and 11th infallible descendants Hazrat Imam Ali Naqi Al-Hadi (p) and Hazrat Imam Hasan Al-Askari (p) in the holy city of Samarra, Iraq.

The protestors, carrying banners declaring "Iraqis stand united in Iraq", also held pictures of the holy shrine before and after the attack, as well as portraits of Marjay Al-Ala Grand Ayatullah Sayyed Ali As-Sistani.

Protest organizer Mohammed Al-Hilli, 27, whose family fled Iraq to Britain when he was two years old, said the event saw both Sunni and Shia Muslims voice their opposition to the attack on the holy shrine.

"The message was very clear. People were in condemnation. They were calling for the perpetrators of such crimes to be brought to justice," Hilli said.

The London march was called after an emergency meeting of Muslim leaders at the offices of the Al-Khoei Foundation, the largest Shia organization in the United Kingdom of Great Britain and Northern Ireland.

Prominent scholars, both Shia and Sunni, attended, as well as Sir Iqbal Sacranie of the Muslim Council of Britain, calling for unity between Muslims.