By Opheera McDoom

KHARTOUM, May 4 (Reuters) - Darfur rebels said on Sunday they had arrested about 13 Sudanese government census staff and would try them as "enemies" in military courts, a crime which could attract a death penalty.

The census began on April 22 for two weeks and is a key part of a 2005 north-south peace deal because it will help determine wealth and power sharing, laying the ground for Sudan's first democratic elections in 23 years due in 2009.

The 2005 deal did not cover a separate conflict in Sudan's western Darfur region. Many in Darfur reject the census because they don't trust the government to implement it accurately.

"Sudan Liberation Movement (SLM Unity) arrested a number of census personnel in the Darfur region and will bring them to trial ...as enemies and their punishment could be death, according to the law of the movement," a statement from spokesman Mahgoub Hussein sent to Reuters on Sunday said.

International experts estimate some 200,000 have died in Darfur and 2.5 million driven from their homes in five years of rape, killing and looting since mostly non-Arab rebels took up arms in early 2003 accusing the central government of neglect.

Khartoum blames the Western media for exaggerating the conflict and puts the death toll at 10,000.

Hussein said there were about 13 in total arrested in South Darfur in the past week. He named three of the detainees.

The head of the census monitoring commission, Abdel Bagi Gailani, said he had heard of one census staff arrested a few days ago and that negotiations were underway to release him.

"I think these (other arrests) may be rumours," he added.

The news of the arrests follows violence on Sunday as government security forces surrounded three Darfur camps in the West Darfur town of Zalengei, firing into the air to try to force people to take part in the census, witnesses told Reuters.

"One man was injured in the leg," camp resident Abdallah Ibrahim told Reuters by telephone.

The army said it was checking the reports, as did the joint U.N.-African Union peacekeeping mission.

The mission, known as UNAMID, is only about a third of its desired strength of 26,000 troops and police, and has been unable to stop clashes between Darfur rebels, militias and government forces in an area almost the size of France.

On Sunday the Darfur rebel Justice and Equality Movement (JEM) said the government had bombed two areas in North Darfur, including a busy marketplace called Shagat Crowe killing 11 people and wounding five.

"This bombardment is systematic," JEM spokesman Ahmed Adam said. "We appeal to UNAMID to carry out their responsibility to protect the innocent people of Darfur."

UNAMID said it was investigating the allegations.

Sudan's army denies any bombardment in Darfur which would be a violation of a U.N. Security Council banning offensive flying.

But on Friday UNAMID confirmed bombing reports last month after evacuating some of the victims. (Editing by Matthew Jones) (For full Reuters Africa coverage and to have your say on the top issues, visit: http://africa.reuters.com/ )

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