Egypt's Coptic Christians, under pressure from repeated attacks by Islamist extremists, are to celebrate the opening of a new cathedral tomorrow – but fear it too may become a target.

The cathedral is said to be the biggest church building in the Middle East and has been largely funded by the Egyptian government, in a sign of its commitment to its Christian minority.

It is located in the country's new administrative capital, a new city being constructed east of Cairo which will grow to a city of 7 million people.

The cathedral will seat more than 8,000 people and features twin bell towers 200 feet high. The opening ceremony will be led by Coptic Pope Tawadros II in the presence of Egypt's President Abdel Fattah el-Sisi and representatives of Islamic authorities.

The project's executive director Wagih Amin, a Christian, told Egypt's The National: 'It is a very great feeling that the president Sisi promised and fulfilled his promise.'

However, reflecting on recent terrorist outrages he added: 'These terrorist incidents destroyed our sense of joy this Christmas, and I expect that other attacks will occur after the mass.'

Security is a major issue at the cathedral, both for tomorrow's service and in future. Thousands of requests to attend the service tomorrow were received and each was carefully vetted, according to Coptic leaders.

However, Maged George, who sits on several Coptic Church committees, said: 'I will go to the Mass at the cathedral and send my children to pray there.' He added that the new building would 'convey a positive message about our citizenship and partnership with fellow Egyptians'.