The White House called for restraint in Egypt on Monday after violent clashes that killed protesters and security forces, and said the transition to democracy should continue.

"As the Egyptian people shape their future, the United States continues to believe that the rights of minorities - including Copts - must be respected, and that all people have the universal rights of peaceful protest and religious freedom," the White House said in a statement.

"These tragic events should not stand in the way of timely elections and a continued transition to democracy that is peaceful, just and inclusive," it said.

The White House also noted Egyptian Prime Minister Essam Sharaf's call for an investigation into Sunday's clashes and his appeal to all parties to refrain from violence.

Egyptian military police raced armored vehicles into a crowd of Christians who were protesting Sunday in response to the partial demolition of a church last month in Aswan, southern Egypt, and demanding that Aswan governor Mostafa al-Sayed be dismissed for failing to protect it.

Christians, and some Muslim activists, said the army had used excessive force, which led to the death of 25 people, most of them Coptic demonstrators. Protesters pelted military police with stones, petrol bombs and set light to army and other vehicles in the worst violence since Hosni Mubarak was ousted on February 11.

The military-backed government says it does not discriminate and has promised to address Christian concerns.

Also on Monday, UN Secretary-General Ban Ki-moon urged Egypt's transitional leaders "to guarantee the protection of human rights and civil liberties" for people of all faiths after Sunday's attacks.

He appealed to all Egyptians "to remain united and to preserve the spirit of the historic changes of early 2011," UN deputy spokesman Eduardo del Buey said.

Christians have long grumbled about discrimination by the state and tensions with the majority Muslims have simmered. But violence has become more common with the rise of strict Salafist and other Islamist groups which Mubarak had repressed.