The head of an ancient Middle Eastern Church has described how "the whole of Syria has become a battlefield" and has appealed to world leaders to intervene in a bid to stop the fighting.

In a statement, Melkite Greek Catholic Patriarch Gregorios III Laham says that the country's "suffering has gone beyond all bounds" and that the conflict "has mown down thousands and thousands" of people – both civilians and military.

The Damascus-based patriarch estimates that, since the conflict broke out two years ago, up to 400,000 Syrian Christians – possibly more than 25 per cent of the total – are either displaced within the country or have fled abroad.

In the statement, which was sent on Monday to Catholic charity Aid to the Church in Need, Patriarch Gregorios reports that since early 2011 more than 1,000 Christians have been killed, that "entire villages have been cleared of their Christian inhabitants" and that more than 40 churches and other Christian centres (schools, orphanages and care homes) lie damaged or destroyed.

He states that key to the country's problems are chaos and insecurity, as well as an influx of "fundamentalist Islamists".

The patriarch declares that the threat to Christianity in Syria has wider implications for the religion's future in the region because for decades the country has provided a refuge for faithful from Lebanon, Iraq and elsewhere.

He states that the conflict poses a severe threat to Muslims, pitting one Islamic tradition against another.

Patriarch Gregorios believes that, in spite of the worsening violence, peace remains possible and, in his statement, calls for action from leaders of Arab nations, Europe, the Americas, world organisations and Nobel Peace Prize winners.

He states: "We are sure that, despite our woes, all [of us] Syrians – government, political parties, Sunni and Shia Muslims, Alawites, Christians and Druze – are capable of engaging in dialogue."

Saying that "there is no safe place left in Syria", he adds: "The whole of Syria has become a battlefield… Every aspect of democracy, human rights, freedom, secularism and citizenship is lost from view and no-one cares."

He states: "Suffering has gone beyond all bounds. The crisis has mown down thousands upon thousands of soldiers, opponents, civilians, men, women, children, Muslim sheikhs and Christian priests."

The patriarch's comments coincide with remarks by fellow Damascus prelate Maronite Archbishop Samir Nassar who, as reported by Fides news agency, said that Christians in Syria "must choose between two bitter chalices: to die or leave".

Archbishop Nassar stressed the threat to both Muslims and Christians from explosives, car bombs, snipers and the lack of medical care following a mass closure of hospitals.

In his statement, Patriarch Gregorios goes on to say that Christians are especially at risk from extremists stirring up riots against them.

He said Christians were particularly susceptible to losing their religious buildings to armed groups for use as "shields" in the conflict.

The patriarch states: "The future of Christians in Syria is threatened not by Muslims but by… chaos… and the infiltration of uncontrollable fanatical, fundamentalist groups."

He refers to large numbers of Christians suddenly being forced to leave their homes and livelihoods adding: "[They have been] able to salvage little if anything.

"By and large, their houses and possessions have been looted, destroyed and damaged. All of this represents a loss of several million dollars."

He states: "In the face of all these dangers, sufferings and misfortunes that affect all citizens, we wonder whether there can be any other way of speaking or acting than that of war, weapons, violence, hatred and revenge. We very much need a solution."

As a Catholic charity for persecuted and other suffering Christians, Aid to the Church in Need has provided ongoing emergency aid – food, shelter and medicine – both in Syria and in neighbouring countries, working through leading bishops in the region.

More requests for aid are being considered by the charity's project coordinators.