Twenty-three Coptic Christians were injured by Muslim extremists Friday after an attack on a church community centre, said an Egyptian bishop.

The attack occurred after a sermon by a radical sheikh and lasted 10 hours before security forces put a stop to it, said Bishop Bejemy to The Associated Press on Saturday. The group of young Muslim men threw firebombs at the Coptic center and at nearby homes in Marsa Matruh, a seaport city in northern Egypt.

According to Egyptian officials, assailants were angry about a new fence erected around the center.

The attack on Copts in Marsa Matruh took place the same day the US Commission on International Religious Freedom issued a statement condemning the Egyptian justice system for not prosecuting violence against Copts.

An Egyptian judge recently acquitted four Muslim men of the murder of a Coptic man. USCIRF called it “the latest example in a growing pattern of instances where individuals have not been brought to justice after committing violent acts against Christians and their property”.

Coptic Christian Farouk Attallah was murdered on October 19, 2009. Attallah’s Christian son was involved in a romantic relationship with a Muslim girl. The Muslim men planned to murder the son, but when they could not find him they killed his father. Despite reported witnesses, the court said there was insufficient evidence and acquitted the men.

“This is one of more than a dozen incidents USCIRF has followed in the last year or so in which Coptic Christians have been the targets of violence,” said USCIRF Chair Leonard Leo, who led a USCIRF fact-finding delegation to Egypt in January. “This upsurge in violence and the failure to prosecute those responsible fosters a growing climate of impunity."

“We call on the government to appeal the verdict in the Attallah murder and bring the perpetrators to justice,” Leo said.

Since 2002, Egypt has been on the USCIRF “Watch List” for its serious religious freedom violations, including widespread problems of discrimination, intolerance, and other human rights violations against members of religious minorities.

According to Egypt’s constitution, Islam is the “religion of the state” and the country’s “principle source of legislation”.

Coptic Christians, who make up about 10 per cent of Egypt’s population, complain that they are discriminated against in all aspects of social life, from education to government representation.

They also voice grievance over the law that requires them to have high-level government permission in order to repair or rebuild churches. Even though they make such requests for permission, Christians are rarely, if ever, granted the right to repair or build churches. Muslims, however, are allowed to freely build mosques without such government permission.