The flames of civil war are rekindling in Angola - and they have potentially serious international consequences. UNITA rebels - fed up with the Angolan government's refusal to discuss a political solution of the conflict - have launched what they call a major offensive against the regime. In turn, the Soviet- and Cuban-backed government says it has launched counterattacks and ''swept'' some areas of rebel activity.
European diplomats confirm the rebel offensive but are unable to provide details. Observers worry that an escalation of the war threatens the status, if not the lives, of some 5,000 Westerners working in Angola. Jonas Savimbi, leader of the National Union for the Total Independence of Angola (UNITA), has repeated a warning that foreigners in the war-affected zones should leave.
Most of the Westerners in Angola are Portuguese, but there are hundreds of Brazilian, American, French, and British diplomats, businessmen, and development officials. Gulf Oil employs at least 400 Americans in the enclave of Cabinda, which is as yet untouched by fighting.
For eight years guerrillas have been striking in other areas of Angola. But the ruling Popular Movement for the Liberation of Angola (MPLA) refuses to acknowledge it is fighting a civil war. It claims to be confronting South African troops supporting groups of local ''bandits.''
But UNITA has some 30,000 guerrilla troops. It receives weapons, ammunition, and logistical support from South Africa and some other African countries.
Intelligence reports suggest the Marxist-Leninist-oriented government gets help from some 30,000 Cuban troops and civilian advisers - with 5,000 of the Cuban troops arriving since late summer. The MPLA denies Cuba has reinforced its troop presence.
Until recently, UNITA leader Savimbi followed a two-pronged strategy. He sought a political compromise with the government but also expanded rebel activity through the southern and central regions of the country. UNITA's territorial expansion was particularly rapid over the past 12 months.
The MPLA has ignored Savimbi's overtures and refused to negotiate over the fate of UNITA's swelling population of foreign prisoners. So the rebel leader declared he will leave the door open for talks, but his forces will push toward Luanda, Angola's capital, seeking a military solution. He has intensified UNITA raids against military, economic, and other strategic targets in the western and northern parts of the country.
UNITA troops now are said to be within 70 miles of Luanda, but recent visiters to the Mediterranean-style city say they did not feel any imminent threat of a siege.
For its part, the government says rebel announcements of successful ambushes against Cuban-Angolan positions and convoys in Cuanza South, Cuanza North, Benguela, Huambo, and several other provinces are ''grossly exaggerated.''
Western diplomats in Luanda, acknowledging the government's claim that UNITA may not be as strong as it claims it is, point out that Luanda maintains administrative capitals in all but one of the country's 18 provinces. UNITA may strike at some of these towns, but it does not hold on to them, diplomats say. Savimbi counters that he is fighting a classical guerrilla war.
Although Luanda is playing down the guerrilla strength, diplomats have noted a considerable increase in the offloading of heavy military equipment in the docks in Luanda. And Cuban-piloted MI-24 helicopter gun-ships and MIG-23 jetfighters have been introduced.
The government has not acknowledged any major new influx of Cuban troops, but it has never published figures on Cuban involvement. Western intelligence sources had put the number of Cubans at more than 25,000.
The Angolan Information Office refutes independent reports that armed guerrillas of the South West African People's Organization and the African National Congress are fighting alongside the Luanda regime.
UNITA says it is holding more than 50 Czech, Brazilian, Portuguese, Spanish, and British civilians in camps in southern Angola. All were said to have been engaged in government development work and captured this year during rebel operations. UNITA also says it is holding two Cuban soldiers.
The International Committee for the Red Cross is trying to arrange for release of the captives as it did earlier this year for a number of captured Czech, Portuguese, and Brazilian men, women, and children.
Savimbi is demanding the liberation of 36 Angolan political prisoners held in Luanda in exchange for the remaining Czechs and refuses to budge until the MPLA makes a conciliatory move. The Red Cross has visited the UNITA captives several times but has apparently not been able to enter government jails.