The Catholic bishop for Sudan's embattled border state of South Kordofan said Tuesday that the government appeared to be waging war on its indigenous Nuba peoples and urged the army to spare civilians.

"As far as I know, President Omar al-Bashir has declared war against the Nuba people," Monseigneur Macram Gassis told AFP.

"If they want to fight the SPLA (Sudan People's Liberation Army -- the southern former rebel army), let them do so. But they should not touch civilians... Why should the women, children and elderly be targeted? These are sacred and they should not be touched," the 72-year-old prelate said.

He was speaking as the United Nations said Khartoum had stepped up its bombing campaign in South Kordofan, the north's sole oil-producing state which has a long border with the soon-to-be independent south, causing "huge suffering" to the civilian population.

The army denied it was targeting civilians, saying that it was simply trying to quell a rebellion.

The heavily-armed state has strong links to the south, especially among the non-Arab Nuba peoples who fought on the side of the SPLA during the devastating 1983-2005 civil war between north and south.

The Nuba are a mixture of Muslims and Christians, unlike their Arab neighbours who are overwhelmingly Islamic.

Activists in Sudan have already warned that the killings taking place in South Kordofan are of a similar nature to attacks carried out by the Sudanese army in the early 1990s, which they say indiscriminately targeted Nuba civilians, including women and children.

The head of the Anglican church, Archbishop of Canterbury Rowan Williams, said on Tuesday that the new Anglican cathedral in the state capital Kadugli had been burned down and warned that the unrest in central Sudan risked becoming "another Darfur."

A number of churches have also reportedly been looted and a pastor from the Anglican Episcopal Church of Sudan, Nimeiri Philip, killed.

Speaking from Khartoum, Gassis said he was not surprised to see those carrying out the attacks "hiding behind the message of jihad," or Muslim holy war.

"Always when there are these kinds of clashes, they say it is foreigners who are helping the rebels, as well as the church. Of course the church does not carry a gun, against anyone. We only want to speak the truth and protect the innocent," he said.

The diocese of El-Obeid covers North and South Kordofan, as well as Sudan's war-torn western region of Darfur, and Gassis said he had witnessed "a lot of cruelty, tyranny, suffering and tears," as the diocesan bishop since 1983.

"After the Comprehensive Peace Agreement (between north and south in 2005) there was a lull in the fighting. Families were reunited and we saw development. Now we are going back to square zero," he warned.

sma/kir