THE latest and most repugnant action by Islamic State (IS) jihadists, the murder of 21 Copts in Libya, has united religious and secular leaders in outpourings of condemnation and statements of solidarity with Christians in Egypt.

President Abdel Fattah al-Sisi, after ordering airstrikes on IS targets in Libya, and declaring seven days of mourning, visited the leader of the Coptic Orthodox Church, Pope Tawadros II, at St Mark's Cathedral, Cairo, to offer his condolences. A statement from the main seat of Sunni scholarship, al-Azhar, said that "such barbaric action has nothing to do with any religion or human values."

The President-Bishop in the Province of Jerusalem and the Middle East, the Most Revd Mouneer Anis, condemned the "heinous murder" of the 21 Egyptians, who were "no different from thousands of other Muslim and Christian Egyptians in Libya seeking employment to support their families".

The General Bishop of the Coptic Orthodox Church in the UK, Bishop Angaelos, said that news of the murders had inflicted "deep feelings of sorrow and pain" within the community. "While every life is sacred, and every death tragic, the particular brutality demonstrated in this instance, and others like it, shows not only a disregard for life, but a gross misunderstanding of its sanctity."

Thirteen of the 21 murdered men came from the village of al-Our, in Upper Egypt. "Our prayers are particularly with the families of these young Coptic men who were fathers, brothers, sons, and friends of many within their tight-knit rural communities," Bishop Angaelos said.

David Cameron, who phoned Bishop Angaelos to offer condolences, said that he was "appalled by the murder of Christians in Libya. . . My thoughts are with the families of those killed, and the UK stands united with the Egyptian people during this period of mourning."

The Presidents of Churches Together in England issued a joint statement on behalf of 43 member Churches, saying that they wished "to stand in solidarity with our brothers and sisters in the Coptic Church as they witness to peace in the midst of violence and brutality."

The Presidents - the Archbishop of Canterbury and the RC Archbishop Westminster; Archbishop Gregorios of Thyateira and Great Britain; the Free Churches Moderator, the Revd Dr Hugh Osgood; Bishop Eric Brown (Pentecostal Church); and Billy Kennedy, of the Pioneer network - called also for prayers "for those who perpetrate such atrocities against those of all faiths and none, that they may understand that each human life is sacred."

Earlier, the Archbishop of Canterbury had condemned "the terrible cruelty of the murders" not only in Libya, but also in Denmark and Nigeria.

Pope Francis on Monday lamented the fact that the 21 Egyptians were "killed simply for the fact that they were Christians. The blood of our Christian brothers and sisters is a testimony which cries out to be heard. It makes no difference whether they be Catholics, Orthodox, Copts, or Protestants. . . Their blood confesses Christ."

The Chief Executive of Christian Solidarity Worldwide, Mervyn Thomas, described the killings as "a senseless and barbaric act of sectarian cruelty against people whose only 'crimes' were being poor and following a different creed. We pray that the perpetrators of these atrocities would recognise the sanctity of human life."

The religious-liberty organisation Release International said that the killings, and the manner in which they were carried out and publicised, were "the clearest indication yet of the policy of brutal religious cleansing of Christians by Islamic State militants."

The CEO of Release, Paul Robinson, described IS as "a death cult" that "glories in the deaths of its own fighters and in the slaughter of its own victims". But Mr Robinson welcomed the statement from al-Azhar condemning the murders, saying that it was "vital that Muslims of learning and goodwill speak up in defence of freedom of faith and religion".

The latest killings carried out by IS represent a further encroachment into the fabric of life in the Middle East. The group is now operating openly in four Arab countries: Iraq, Syria, Yemen, and Libya. But social-media messages indicate that it has followers and sympathisers in many more.

The priority for these states is to prevent contagion. On Monday, Saudi Arabia and several Gulf states condemned the Libyan killings, and the Saudi government on Wednesday was hosting a meeting of defence chiefs from the 22-member anti-IS alliance to discuss joint strategies. President Sisi has called on the international community to join Egypt in taking military action against IS in Libya, as is happening in Iraq.

The other new dimension of IS action is the fact that Arabs are now targets: first, the captured Jordanian pilot in Syria, and now the Egyptian Copts in Libya. This factor, more than any other, is likely to increase the revulsion felt by the overwhelming majority of Arabs and Muslim towards the brutal tactics of the jihadists, and dampen popular support for them.