Fresh fighting has broken out in the northern Nigerian city of Kaduna, after Monday's march by Christians protesting against the proposed introduction of Islamic law erupted into violence.

Dozens of bodies lay on the streets as police struggled to quell riots between Christians and Muslims, Reuters news agency reported.

"In the working class Sabo district, I saw police open fire indiscriminately on Muslim and Christian gangs but neither side appeared to retreat and corpses littered the streets," Reuters correspondent Felix Onuah said.

With police admitting the situation is desperate, latest reports say the Nigerian army has now deployed troops in Kaduna to assist them in controlling the violence.

Police said troops from the One Mechanised Division based in Kaduna had been sent to help restore calm as the state government ordered businesses and schools to shut.

Police say they picked up 25 bodies from the streets overnight.

Curfew

Last night the authorities imposed a dusk-to-dawn curfew and warned that anybody found on the streets after dark would be "decisively dealt with".

But the curfew was ignored in parts of the city where Christian and Muslim gangs set up roadblocks.

Several buildings - including churches and at least one mosque - were seen burning in the town on Tuesday.

"I am appealing to the Christian and Muslim leaders to caution their followers and desist from the ongoing riots," Mr Shekari said in a broadcast on local television.

The violence came after thousands of Christians took to the streets protesting against the proposed introduction of Islamic law in the state of Kaduna.

Eyewitnesses said counter-chants by Muslims who support Sharia quickly degenerated into fighting.

Market ablaze

The main Kaduna market was set on fire and several cars bearing Islamic slogans were attacked.

Speaking from his office in Kaduna, Human Rights Monitor spokesman Festus Okoye said there had been massive destruction.

Despite the fears of Christians, the state governor has made no firm commitments to establish Sharia law in Kaduna, but has set up a committee to study how it might be implemented.

The Sharia issue has become increasingly divisive in Nigeria since the announcement last October by another state in the north, Zamfara, that it would introduce the code.

Sharia courts began operating in Zamfara last month.

Sensitive area

Although several rural states in northern Nigeria which are overwhelmingly Muslim have already announced their intention to introduce Sharia, Kaduna is a far more sensitive and politically important state.

The city of Kaduna is one of the largest in northern Nigeria, and the state has a substantial indigenous Christian population.

Muslims have repeatedly stressed that Sharia will not affect Christians. They say that the Nigerian press, mainly controlled by Christians from the south of Nigeria, has exaggerated the issue.