The leader of Egypt's Coptic Christians has accused the country's president of "negligence" following deadly clashes outside the main cathedral in Cairo.Pope Tawadros II said Mohammed Morsi had failed to protect the building, where two people died after being attacked by an angry mob of Muslims.The remarks were the strongest issued against President Morsi by Pope Tawadros since he took office in 2012.The weekend clashes between Muslims and Copts were Egypt's worst in months.The two people - at least one of whom was a Christian - were killed after attending a funeral for four Christians who died in sectarian violence in Khosous, about 10 miles (15km) north of Cairo, the previous day.A Muslim was also killed in those clashes, which began after inflammatory symbols were drawn on an Islamic institute, provoking an argument.The dispute escalated into a gun battle between Christian and Muslim residents, while Christian-owned shops were also attacked.Coptic Christians, who make up about 10% of the population, have long complained of discrimination and have suffered an increase in attacks by Muslims since the fall of President Hosni Mubarak in 2011.'Action not words'In a telephone interview on the private ONTV channel, Pope Tawadros said Mohammed Morsi had "promised to do everything to protect the cathedral but in reality we don't see this".He said the failure to do so "comes under the category of negligence and poor assessment of events"."We need action not only words... There is no action on the ground," he said, adding that "the Egyptian Church has never been subject to such [attacks] even in the worst ages".The violence erupted on Sunday when mourners leaving St Mark's Cathedral clashed with local residents.Police fired tear gas to break up the violence. More than 89 people were injured, the state news agency said.Mourners inside the cathedral had earlier chanted slogans against President Morsi.Witnesses told local TV stations that the violence started when a mob attacked the Copts as they left the cathedral, pelting them with stones and petrol bombs.The Christians responded by throwing stones back, the witnesses said, until police arrived and attempted to quell the unrest, firing tear gas into the cathedral compound.Afterwards, Mr Morsi denounced the violence in a phone call to Pope Tawadros."Any attack against the cathedral is like an attack against me personally," he was reported as saying. He also called for an immediate investigation.The Islamist Freedom and Justice Party (FJP), the political arm of Mr Morsi's Muslim Brotherhood movement, posted a statement on its Facebook page stressing its "utter rejection and condemnation of violence".