KINSHASA, Democratic Republic of Congo (CNN) -- A Tutsi-led revolt against President Laurent Kabila spread to the west of the Democratic Republic of the Congo on Thursday, with fighting in an oil town and a naval base on the Atlantic Coast. Two American workers reportedly were taken by rebels.

A senior government official said that Kabila loyalists were fighting Rwandan-backed rebels in Muanda near Angola's Cabinda enclave and in the nearby naval base of Banana.

"We are fighting very seriously there. There is a big battle and we are in a position of force," the official told Reuters.

Diplomats and industry sources reported that Muanda had fallen on Wednesday and that two Americans working for the Chevron oil company were in rebel hands.

"We have information that the rebels have captured both the town of Muanda and the naval base at Banana," one industry source said.

The government official said that reinforcements were being sent to the east, where the revolt erupted on Sunday in the town of Goma on the border with Rwanda and spread to nearby Bukavu.

He said that the third city of Kisangani in the jungle interior was quiet and in government hands on Thursday after two days of fighting centered on the airport outside town. However, unconfirmed reports spoke of fresh fighting there.

In Kinshasa, supporters of Kabila took to the streets of the capital, which emerged from a third and possibly final night of curfew imposed after shooting there on Sunday and Monday.

Kabila's government threatens war

Thursday's fresh round of fighting followed a threat of war against Rwanda by Kabila's government.

Government spokesman Didier Mumenge warned Thursday that Congo would "extend the war into Rwanda" unless the international community pressured the tiny country to withdraw Rwandan troops allegedly deployed in Congo.

Speaking to reporters, Mumenge described Rwanda as a "criminal state" that had meddled in foreign affairs while drawing on "a feeling of pity by the international community" after the 1994 Rwandan genocide.

He was referring to the ethnic slaughter of more than half a million people, mainly Tutsis, by Rwandan Hutu soldiers and militants who were subsequently driven into hiding, from where they have persistently attacked Rwanda's Tutsi-led government.

"From now on, the war will no longer be fought by the Congo Armed Forces but that of all people in the Congo," Mumenge said.

Rwanda's Tutsi-dominated army and Congo's ethnic Tutsi Banyamulenge community have spearheaded the seven-month bush war that toppled veteran dictator Mobutu Sese Seko and propelled Kabila to power in May 1997.

The Banyamulenge are at the forefront of the latest revolt which follows a July 27 order from Kabila for Rwanda to withdraw all its soldiers from the former Zaire.

Kabila's administration accuses Rwanda of fomenting the revolt and sending troops to back the Banyamulenge.

Rwanda's President Pasteur Bizimungu denied Wednesday that his country was involved in the conflict but was noncommittal about whether it would intervene in the future.

Other developments

• The United States, expressing concern at the regional implications of the crisis, urged Congo's neighbors to stay out of the conflict.

  "We urge all countries in the region to respect the territorial integrity of the Congo, refrain from becoming involved in the conflict and respect international law," deputy State Department spokesman James Foley said in a statement.

• The rebels on Wednesday put a political face to their armed campaign by naming opposition politician Arthur Z'Ahidi Ngoma as coordinator of the rebellion -- a title Kabila once enjoyed.

  A former staff member of the U.N. Educational, Scientific and Cultural Organization (UNESCO), he heads the Forces of the Future party.

• African leaders plan to meet in Zimbabwe on Friday to discuss the crisis, with Kabila among those invited.

The Associated Press and Reuters contributed to this report.

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