The kidnappers of nine Chinese oil workers in Sudan panicked when they saw a military aircraft fly overhead and killed five of their hostages, a Sudanese government official said, contradicting Chinese claims of a botched rescue attempt.

The aircraft was monitoring the hostages, said Mohammed Doureik, the commissioner of Abyei in the province of south Kordofan where the Oct. 18 kidnapping took place.

"There were no clashes. There was a slight panic when they saw the plane and they killed the them," said Doureik, who has been following negotiations with tribal leaders for the release of the remaining hostages.

Two hostages had escaped and a third was handed over Tuesday to local tribal chiefs, leaving the ninth Chinese oil worker unaccounted for, he added.

China, however, say the kidnappers killed five of the nine hostages during a Sudanese rescue operation.

Foreign Ministry spokeswoman Jiang Yu said China was involved in the rescue attempt, but declined to say if the Chinese government had been in contact with the rebels and refused to give further details. She said China had a working group in Sudan at the time of the rescue.

The deaths are one of the most violent acts China has faced in recent years as its businesses expand worldwide to buy energy and other raw materials or find new markets.

Sudan's Defense Minister Abdel Rahim Hussein called the slaying a "terrorist act," and Foreign Ministry officials said there will be new measures to protect foreign interests in Sudan.

China's presence in Sudan has become a target of disaffection by anti-government forces in Darfur who maintain its investment is helping the government.

China buys nearly two-thirds of Sudan's oil, providing crucial revenue to the government which involved in a civil war in the Darfur region, where 300,000 people have been killed and 2.5 million displaced.

Sudan's government has blamed rebels from Darfur for kidnapping the Chinese, but on Tuesday a spokesman for the rebels denied involvement.

"Even though China has become a partner in supporting the government military offensive in Darfur, we remain committed to international laws ... and we condemn such an attack," said Ahmed Hussein, spokesman for Justice and Equality Movement, which the government specifically accused of the kidnapping.

A tribal leader from Kordofan told The Associated Press the kidnappers belonged to a local militia that claims it is neglected and demands jobs and benefits.

Jiang said China would not cut its business ties with Sudan, saying they were beneficial to both countries.

"We have actually played a constructive and contributing role in Sudan's economic and social development. Our companies have brought a lot of benefit to the local people and we will continue to keep our friendly cooperation with Sudan," she said.