A protest by Egyptian Christians against attacks on churches turned violent in Cairo Sunday. Reuters/Amr Dalsh

Clashes between Coptic Christian protesters and Egyptian security forces killed at least 24 people and injured 200 in Cairo Sunday, authorities said.

Several hundred Christians took to the streets to protest a recent attack on a church and the recent demolition of a church in Aswan. Their demands included for the church to be rebuilt and the governor of Aswan removed.

Reports from Cairo suggest some of the protesters may have snatched weapons from soldiers and threw rocks and bottles at them.

Three soldiers were shot dead and dozens were wounded, according to state television.

The death toll from the violence was at least 24, the AP reported, citing a Health Ministry official.

More than 1,000 Egyptian security forces with armoured vehicles were deployed along the Nile, and as the protesters refused to back down, the military imposed a curfew from 2 a.m. (0000 GMT Monday) until 7 a.m. local time in the area from Maspero to Abbassiya square in central Cairo, Agence France-Presse reported.

In a televised speech, Prime Minister Essam Sharaf denounced "unjustified violence" that "raised fear and concerns about the future of this homeland" and could endanger Egypt's transition to democracy.

The demonstrations had started peacefully with a march and a sit-in at the state television building in the centre of Cairo, but violence mounted after the protesters came under attack by men in plainclothes who pelted them with stones, according to demonstrators cited by AP.

Some protesters resorted to setting military vehicles on fire while the military fired into the air to disperse the crowds, according to reports.

Similar protests also broke out in four other provinces in Egypt, according to Al Arabiya television.

Hundreds of Copts also took part in a protest last Tuesday in Cairo after a church was burnt in Merinab, in the southern province of Aswan.

The church was attacked after Aswan Gov. Mustafa al-Seyyed reportedly said Copts had built it without the required planning permission, according to state television.

Sectarian clashes are frequent in Egypt, and in May 15 people died after Muslim protesters attacked two churches because they believed the Christians were detaining a Muslim convert.

In January, 20 people were also killed outside a church in Alexandria in a suicide bomber attack.

Coptic Christians are the largest religious minority in the Middle East and account for about 10 per cent of Egypt's population, but they have for long complained of oppression and discrimination.

Christians accused the regime of former President Hosni Mubarak, who was ousted in February, of actively encouraging religious discrimination by failing to prosecute perpetrators of violence against them.

The regime also failed to redress laws which discriminate against Christians, particularly with respect to church construction, which require presidential permission, and church renovation, according to a U.S. State Department report.

The transitional military regime however denied the clashes were sectarian as the prime minister instead blamed them on troublemakers, raising fears tensions could continue to escalate.

"What is happening now is not clashes between Muslims and Christians but attempts to spark chaos and strife among the homeland sons," Sharaf wrote on his Facebook page. "I call upon Egyptians to not respond to the calls for strife."

"This is not befitting the children of the homeland who remain and will remain a single hand against the forces of vandalism... and extremism," Sharaf said.