The deaths of the Chinese at the facility near the border with Somalia underscored the vulnerability of a rapidly growing Chinese presence across Africa, particularly in unstable areas where oil is being sought or produced.

Witnesses said dozens of rebel gunmen crept up to the facility around dawn and unleashed an intense barrage of machine-gun fire at Ethiopian soldiers posted outside. After a fierce hourlong battle, the rebels rushed away, taking with them seven Chinese hostages and a number of Ethiopians.

The Chinese working at the facility, in a remote area not far from the trading town of Jijiga, were part of a large Chinese presence on the continent that aims above all at gaining access to energy sources vital to the booming Chinese economy.

“The Chinese are going places where nobody else will go,” said Peter Brookes, a former deputy assistant defense secretary in the Bush administration who has studied the matter. “People don’t really want to go into Sudan, the Niger Delta, but the Chinese are willing to go to these places where others, for political or stability reasons, won’t go.”

Several Chinese workers have been kidnapped in Nigeria’s volatile Niger Delta.

Ethiopia, a close American ally, has been wracked by separatist violence for years, but the severity of this attack seemed to unnerve the government, whose officials usually play down any threats to their control.

“It was a massacre,” said Prime Minister Meles Zenawi in a broadcast address. “It was cold-blooded murder.”

The Ogaden National Liberation Front, a militant group fighting for independence for part of eastern Ethiopia, immediately took responsibility, saying in an e-mail: “We will not allow the mineral resources of our people to be exploited by this regime or any firm that it enters into an illegal contract.”

The attack came at a precarious time for Ethiopia. Thousands of Ethiopian troops are bogged down in Somalia, where they face increasing resistance as they shore up the embattled government there. On Tuesday, a suicide bomber apparently targeting Ethiopian troops killed seven civilians in Mogadishu, the Somali capital, the second suicide attack there in a week.

Ethiopia’s intervention in Somalia, analysts said, may have sparked the rebel attack on the oil facility. Ethiopian troops have recently rounded up dozens of separatist rebels captured in Somalia, including many members of the Ogaden National Liberation Front.

“This is the rebels’ response,” said Ted Dagne, a specialist in African affairs for the Congressional Research Service. “They are fighting a classic guerrilla war against the government and those widespread detentions became another one of their grievances.”

The Ogaden has been a contested area for decades, home to Somali-speaking people who accuse the Christian-led Ethiopian government of persecuting them because they are Muslim.

The Ogaden National Liberation Front asserts that the government has targeted civilians and burned Ogadeni villages. Western military analysts estimated that the front has several thousand fighters who receive weapons from Eritrea, Ethiopia’s neighbor and bitter enemy, and find sanctuary in Somalia.

Xinhua, China’s state-run press agency, confirmed that at least nine Chinese workers were killed at the oil facility. The rebels briefly seized control of the facility before kidnapping the workers, who were among the facility’s 37 Chinese and 120 Ethiopian employees.

With China’s involvement growing in Africa, its workers often operate in unstable regions. The facility attacked Tuesday appeared to be an example of Beijing’s willingness to run risks even when profit prospects are unsure. The region is known more for its instability than its oil. But the Ogaden National Liberation Front seemed to want to send a message to the Chinese and others considering investing in eastern Ethiopia, saying that the Ethiopian government “is not in effective control of the Ogaden.”

“Oil investments in Ogaden will result in a similar loss,” the group said.

In recent years, Chinese companies have invested hundreds of millions of dollars in projects across Africa. From Angola to Kenya, and Sudan to Zimbabwe, the Chinese have built or promised to build railroads, roads, refineries, hospitals and communication networks, often working with authoritarian governments deemed objectionable by the United States and Europe. They also have been willing to undertake projects too small to interest others.

Much of the Chinese activity has focused on energy, but Beijing also has helped countries, including Ethiopia, with few known energy resources. Such assistance is seen as useful in opening African markets to Chinese goods. Beijing also hopes its African allies can bolster its political clout in international venues like the United Nations.

China has courted Africa at the highest levels. President Hu Jintao visited eight countries there in February. Three months earlier, Beijing acted as host for a summit meeting attended by almost every African head of state. China now trails only the United States and Europe as the continent’s leading trading partner.

The Chinese presence, however, has not been universally welcomed. Workers in Chinese-run mines in Zambia have protested wage and working conditions. African producers complain that cheap Chinese goods are flooding their markets, contributing to unemployment. They say Chinese contractors underbid local companies and often import cheap labor.

President Thabo Mbeki of South Africa has warned that Beijing was running the risk of creating a “colonial relationship” in Africa.

Brookes said: “Some people are not very happy. There have been riots over the Chinese presence.”

—
Brian Knowlton reported from Washington.