By Tim Witcher (AFP) – 14 hours ago

UNITED NATIONS — UN troops are to be moved to the tense north-south Sudan frontier to head off violence ahead of a referendum that could break up Africa's biggest nation, a top UN official said.

But cracks in international unity over Sudan appeared when China objected to a UN Security Council resolution on a committee monitoring sanctions against allies of Sudan's President Omar al-Bashir.

Extra troops were ordered to "hotspots" on the frontier after the council was told that the south's leader feared a war with the north over the looming independence referendum.

US ambassador Susan Rice said the southern Sudan region's president Salva Kiir had asked for a frontier buffer zone with only UN troops when he met Security Council ambassador's last week.

"President Kiir also warned that he fears the north may be preparing for war and may be moving troops southward," Rice told the council.

After the meeting, UN peacekeeping chief Alain Le Roy said UN troops would be moved toward the border within weeks.

"We will increase our presence but only in some hotspots," Le Roy said. The UN mission, UNMIS, did not have enough troops to create a buffer zone along the whole 1,250 mile (2,000 kilometer) north-south border.

Rice said Security Council members had been "skeptical" that a force along the entire border could be organized.

She said any force changes should "focus on those areas along the border that are most vulnerable or at high risk of violence."

Southern Sudan and the nearby Abyei region are to hold a referendum on January 9 on whether they want to break with the Arab-dominated north.

The votes are widely expected to lead to secession, but preparations are seriously behind schedule and Western nations fear a conflict if there is a delay. The north and south have accused each other of starting a military buildup.

UNMIS has about 10,600 troops and police in Sudan monitoring a 2005 peace accord which ended two decades of civil war between the north and south. Some two million people died in the conflict.

The Security Council, including the main powers -- the United States, China, Russia, Britain and France -- went to Sudan last week to give a united message that the referendum must be held on time.

A senior US official said the United States was looking for ways to strengthen the application of UN sanctions against Sudan if there is a delay.

China, however, abstained in a Security Council vote on Thursday on extending the mandate of experts overseeing existing sanctions against Sudanese figures under travel and assets freezes because of their action in the Darfur war. There is also an arms embargo on Darfur.

Sudan's president is not on the sanctions list but is wanted by the International Criminal Court for genocide and war crimes in Darfur.

China is the major buyer of Sudanese oil and has other key commercial interests.

"China has serious concerns about the annual report submitted by the panel of experts on the Sudan sanctions committee and believes that there is much room for improvement in the work of the panel," a Chinese official told the Security Council, to justify the abstention.

"We urge the panel of experts to conduct their work under the principles of objectivity and responsibility," the official added, without giving any details.

China could have vetoed the resolution as one of the permanent members of the council. The abstention signaled its strong concern.

Rice said the new resolution includes measures that tighten enforcement of the arms embargo, "including language to make clear the scope of the current embargo and clarify obligations of the government of Sudan and other member states? under the sanctions regime."

She added: "Although the panel has faced setbacks in Sudan and restrictions on mobility, their presence and reporting reaffirms the Council's commitment to the safety and protection of the people of Darfur."

A senior US official said earlier that there are "additional measures" that could be applied if the referendum is delayed.

"I think it is fair to say that neither the international community, neither any individual member state is without some leverage," said the official speaking on condition of anonymity.