UN Under-Secretary General for peacekeeping operations Hervé Ladsous on Wednesday warned of a rapidly worsening security situation and large-scale displacement in Sudan's Darfur region.

In a briefing to the UN Security Council, Ladsous said fighting the government and the Sudan Liberation Army/Abdel Wahid (SLA/AW) rebel group has escalated dramatically, especially in the mountainous Jebel Marra region.

Humanitarian organizations estimate that at least 138,000 people Jebel Marra were newly displaced as of 31 March, Ladsous explained.

Ladsous said the number of casualties was unknown because the government had blocked access to the joint UN-African Union peacekeeping force known as UNAMID - which was involved in compiling the briefing report - and humanitarian organizations. However, he said, it was clear there had been continued clashes and aerial bombardments.

Enemies each claim upper hand

Jebel Marra straddles three Darfur states - North Darfur, Darfur Central, and South Darfur - where most of the refugees are said to have fled. The Sudanese government claims it has taken control of Jebel Marra in its entirety. However, the rebels - who have capitalized on gold mined in the region to illicitly raise funds - say they have pushed back government forces.

The peacekeeping chief also said UNAMID had found that the situation in other parts of Darfur was also tense.

"The security situation in other parts of Darfur remained fragile with underlying tensions among and between local tribes over the access to, use and management of land, water and other resources, leading to persistent outbreaks of inter-communal conflicts despite measures taken by the local authorities to contain the clashes," said Ladsous.

Ladsous noted that the political process to settle the conflict remained "polarized." Efforts towards finding a peace had involved the UN, African Union and the government, said Ladsous. However, "progress in political efforts to reach a sustainable resolution of the conflict through inclusive dialogue remained elusive."

Al-Bashir remains defiant

A referendum on Darfur's administrative status is scheduled to take place from 11 to 13 April. The vote is to determine whether Darfur becomes a single region or retains its current five subregional divisions.

Al-Bashir maintained that the UN figures on internal displacement were inflated

In an interview with the BBC published Thursday, Sudanese President Omar al-Bashir challenged accusations that his armed forces had bombed and torched villages. He also dismissed UN figures about the number of people displaced as exaggerated.

The president, who remains wanted by the International Criminal Court for alleged human rights violations, said UN peacekeepers and aid workers should leave the region. "

As peace has returned to Darfur, I think that they have no role to undertake," he said.

Darfur has been in turmoil since 2003, when ethnic Africans rebelled - accusing Sudan's Arab-dominated government of discriminating against them. Khartoum is alleged to have responded by giving arms to nomadic Arab tribes - known as the janjaweed, to use against the local population. The UN says at least 300,000 people have died as a result of the conflict, with 2.6 million having fled their homes.