(Adds JEM denying it carried out the attack)

By Alaa Shahine

KHARTOUM, Oct 27 (Reuters) - Kidnappers killed five Chinese oil workers on Monday out of nine they had been holding hostage in central Sudan for more than a week, the Sudanese Foreign Ministry said.

The ministry blamed the Justice and Equality Movement (JEM), a Darfur rebel group, for seizing and killing the Chinese. A London-based JEM official denied the group was involved.

"Five were murdered. Two were able to escape with minor injuries," ministry spokesman Ali al-Sadig said. The two workers who escaped were now in the hands of the government, Sadig said while the kidnappers were still holding the remaining two. "This incident happened without any provocation," he said.

The government and rebels routinely trade accusations of human rights violations in Darfur, where a bloody conflict has raged since 2003.

The kidnapping was the third such incident in the energy-producing state of South Kordofan in the past year. Analysts say the underdeveloped region, which borders Darfur, could become another violent flashpoint.

The nine workers were snatched near a small oil field where they were doing contract work for the Greater Nile Petroleum Operating Company (GNPOC). The company is a consortium led by China's CNPC that also includes India's ONGC, Malaysia's Petronas and Sudan's state-owned Sudapet.

Sadig said the kidnappers had demanded that Chinese oil firms leave the region.

"STRONGLY CONDEMNED"

The Chinese embassy in Khartoum could not be reached for comment, but China's Xinhua news agency said the embassy "strongly condemned" the killings. China is the biggest foreign investor in Sudan and one of Khartoum's strongest allies.

El-Tahir el-Feki, a JEM official, said the group had not authorised any attack on Chinese workers.

"Maybe there are elements who say they are members of the group without its knowledge," he told Reuters.

The Darfur rebel group has said it had forces in the area and warned that oil workers were legitimate military targets.

JEM seized five oil workers -- an Egyptian, an Iraqi and three Sudanese -- in October 2007 but released them.

Local tribesmen have identified the head of the kidnappers as a man called Fudeili, a member of a sub-clan of the Arab al-Misseriya tribe called Awlad Omran.

Local officials said the kidnappers probably wanted oil money. The consortium produces more than 300,000 barrels of crude per day (bpd) in Sudan's Blocks 1, 2 and 4. Sudan produces about 500,000 bpd of crude.

Abdul-Rasoul al-Nur, a former governor of Kordofan and a Misseriya leader, said his tribe condemned the killings.

"Even if the demands (of the captors) were just, the wrong methods obstruct reaching those just demands. This is a huge mistake," he told Reuters.

The International Crisis Group think-tank said last week the a 2005 peace deal that ended two decades of war between north and south Sudan was at risk in South Kordofan "where many of the same ingredients" that produced the Darfur conflict existed.

South Kordofan is inhabited by Arab and African tribes who were mobilised during the north-south war and who remain polarised along tribal and political lines, the group said.

The Sudanese Foreign Ministry said Sudanese authorities would take "more security measures" to protect Chinese and foreign workers.

A group of kidnappers seized four Indian oil workers and their Sudanese driver in May. Three men managed to escape and one was released. Another man is believed dead. (Additional reporting by Firouz Sedarat in Dubai; Editing by Giles Elgood) (For full Reuters Africa coverage and to have your say on the top issues, visit: http://africa.reuters.com/ )

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