Over 100 Islamic leaders have signed an open letter urging British Muslims not to travel to Syria or Iraq to join in the sectarian violence

Both Sunni and Shia Imams have joined the call, with an unprecedented display of unity as they "urge British Muslims not to fall prey to any form of sectarian division or social discord".

"The month of Ramadhan is a time of reflection and compassion for humanity," the letter states.

"The ethos of this month is to demonstrate generosity and solidarity especially towards those who are less fortunate.

"Ramadhan...teaches us the value of unity and perseverance and we urge the British Muslim communities to continue the generous and tireless efforts to support all those affected by the crisis in Syria and unfolding events in Iraq, but to do so from the UK in a safe and responsible way."

Over 2,400 people were killed in Iraq in June, which marks it as the deadliest month the country has experienced in years.

Sunni Muslims have captured several key northern cities amidst escalating violence and, according to the BBC, security services estimate that around 500 Brits have now travelled to Syria to join the fight.

A video was recently posted online in which three young British men, none more than 20-years-old, called for others to join them in Syria where they are fighting for insurgent group Islamic State in Iraq and the Levant (ISIS), which is attempting to found a pan-Islamic state across a stretch of northern Iraq and Syria under the leadership of Abu Bakr al-Baghdadi.

Concerns have been raised that other young Brits may travel abroad to train under Islamic extremism.

In an interview with Radio 5live, one man - allegedly from West Yorkshire - claimed that he has been training with al-Qaeda linked the al-Nusra Front in Syria for the past year. He described Britain as "pure evil" and referred to the 7/7 London bombers as "heroic lions".

In an alarming speech he went on to declare: "If and when I come back to Britain it will be when this khilafah, the Islamic state, comes to conquer Britain, and I come to raise the black flag of Islam over Downing Street, over Buckingham Palace, over Tower Bridge and over Big Ben."

Earlier this week, the leader of ISIS declared that Muslims will continue fighting until they conquer Rome.

Abu Bakr al-Baghdadi used his latest message to call his radical followers to "rush" to join his side.

"Rush O Muslims to your state. Yes, it is your state. Rush, because Syria is not for the Syrians, and Iraq is not for the Iraqis. The land is for the Muslims, all Muslims," he urged.

"This is my advice to you. If you hold to it you will conquer Rome and own the world, if Allah wills.

"O Muslims everywhere, whoever is capable of performing hijrah to the Islamic State, then let him do so, because hijrah to the land of Islam is obligatory...immigration to the house of Islam is a duty."

Qari Mohammed Asim, of the Makka Mosque in Leeds, was one of the key Imams who drafted the open letter. He has urged Muslims of all denominations to unite against the violence.

"The scale of the humanitarian disaster in Syria and the escalating violence in Iraq calls for an unprecedented response. As we near the end of the first week of Ramadan our message is simple, we have come together to urge British Muslim communities not to fall prey to any form of sectarian divisions or social discord," he has said in a statement.

"Here in the UK we are Sunnis and Shias, brothers in Islam – and brothers in Britain too. The conflict in Syria and Iraq can never change that no matter how bitter the fighting. We urge members of the community to echo this sentiment by adding their signature to this letter, joining the many others that have done so already."