U.N. officials, deeply concerned over intensified fighting in the Angolan provinces of Huambo and Bie, wondered Tuesday whether anything could be done to prevent the return of a full-scale civil war throughout the country.

U.N. officials have warned for months that Angola’s warring parties – especially the rebel National Union for the Total Liberation of Angola (UNITA) – were headed for war after several years of relatively minor clashes and a formal cease-fire.

With reports mounting of UNITA victories in Huambo and Bie and the rebels’ attempt to cut off the city of Kuito, U.N. special envoy Issa Diallo and a ‘troika’ of concerned outside countries – Russia, Portugal and the United States – issued a stern warning Tuesday about the new oubreak of fighting.

“Men, women and children are again forced to flee into the unknown, risk encountering landmines and possible attacks, in need of food and shelter – or they risk losing their lives if they stay in their villages and towns,” Diallo and the troika said in a joint statement.

The statement urged UNITA and the Angolan government to allow independent assessment of the humanitarian situation on the ground. It added, however, that the U.N. Observer Mission (MONUA) “has been forced to withdraw from Kuito and surrounding areas.”

The United Nations warned that a major humanitarian crisis could be in its initial stages, with more than 400,000 Angolans having been driven from their homes in the recent fighting. But

U.N. Secretary-General Kofi Annan also sounded pessimistic about the ongoing international effort to maintain the country’s increasingly symbolic cease-fire.

“There is a war,” Annan acknowledged Monday in commenting on the Angolan situation. He said that UNITA has regrouped its forces and argued that the UN’s role was hindered by the fact that he was unable to enter into direct communication with UNITA or its leader, Jonas Savimbi.

Annan said the Security Council would now have to decide “whether the United Nations has a role to play or not.” Several members of the Council, including the United States, were considering withdrawing the more than 7,000 U.N. peacekeepers currently deployed in the country.

The mercurial Savimbi refused to be contacted even by satellite phone, arguing that the Angolan government might try to locate and kill him. According to U.N. sources, the UNITA leader – apparently based in the central town of Bailundo – has once again isolated himself and his followers from outside contact in preparation for renewed war.

If full-scale war returned to Angola, it would be the second time that the peace process had broken down while U.N. peacekeepers were deployed to prevent such a collapse. After UNITA lost 1992 elections to the leftist Popular Movement for the Liberation of Angola, Savimbi led the rebels back to war. Some 500,000 Angolans died before both sides re-committed themselves to peace in 1994.

The second peace process always was in a precarious position, with the Angolan government accusing UNITA of refusing to turn in its best weapons and retire its corps of soldiers.

The United Nations estimated UNITA rebels could still field some 30,000 troops, while the government’s 90,000 soldiers were spread thinly throughout the country and deployed in conflicts in the neighbouring Congo-Brazzaville and the Democratic Republic of the Congo, formerly Zaire.

The flaws in the peace process became more apparent in June, when U.N. envoy Alioune Blondin Beye, the negotiator of the 1994 peace pact, died in a plane crash in Cote d’Ivoire while trying to warn African governments about the threat of a new Angolan war.

After Beye’s death, UNITA moved to reclaim towns turned over to government control and broke-off contact with the troika and with more moderate UNITA politicians, who set up a Luanda-based splinter group.

Human rights groups, meanwhile, faulted the United Nations for not doing enough to prevent the re-arming of both sides. The government has been able to pay for new arms purchases through its control of Angola’s oil-rich eastern zones, while UNITA has parlayed its wealth in diamonds to circumvent a U.N. arms embargo imposed against it.

On Monday, UNITA – which has reportedly acquired U.S. Stinger missiles – shot down an Antonov-12 transport plane carrying government troops and supplies. U.N. officials warned that both sides are massing troops more heavily in central Angola, even though neither side has been able to secure a decisive military advantage over the other since the country’s 1975 independence.