Who are the Copts?

The Coptic Orthodox Church of Alexandria - to give it its full name - is among the oldest branches of Christianity. According to tradition, it was founded in Egypt by St Mark the Evangelist in around AD42. The term"Coptic" refers to an ethnic group indigenous to North Africa and living in Egypt at the time, and also to the language they spoke. The Copts are still the largest Christian community in the Middle East and North Africa today, with significant numbers in Libya and Sudan as well as Egypt.

Why do they celebrate Christmas on a different day?

While Western Christianity follows the Gregorian calendar (named after Pope Gregory III, who introduced it in 1582), the Copts use the older Julian calendar adopted by Julian Caesar in 45 BC. The Julian year is 11 minutes too long so over time, it has grown out of sync with the Gregorian version, which is why the Copts - along with the Eastern Orthodox churches - celebrate Christmas two weeks later, on January 7.

Who is their leader?

The Copts have their own pope. The current head of the church is Tawadros II, who became the 118th Coptic pope on November 4, 2012.

Are the Copts persecuted?

Relations with Muslims are at a low point in Egypt, where Christians make up about ten per cent of the population. They have been increasingly marginalised since Gamal Abdel Nasser seized power in 1952 and have fewer rights than the Muslim majority. Until 2005, Christians had to have presidential approval to carry out even minor repairs on churches. Members of the US congress have expressed concern about the trafficking of Coptic women and girls into sexual exploitation, forced conversion and forced marriage to Muslim men. It has been alleged the police collude with the traffickers.

Copts are increasingly the target of militant Islamists, including ISIL and terrorist groups fighting in the Sinai insurgency.

Notable Copts: Boutros Boutros Ghali, former secretary-general of the United Nations, heart surgeon Sir Magdi Yacoub and Dina Powell, deputy national security adviser to US president Donald Trump.