MONROVIA, LIBERIA, JUNE 7 -- Renewed fighting between government and rebel forces was reported today at a key Firestone rubber plantation 30 miles southeast of Monrovia as dozens of American citizens and other foreign nationals departed this strife-torn West African nation by a special charter plane bound for neighboring Ivory Coast.

{The United States has informed the Soviet Union and a number of West European and African nations that it will help evacuate their diplomatic personnel from Monrovia if such a pullout becomes necessary, State Department spokesman Richard Boucher said in a briefing in Washington.}

The report from diplomats of new fighting outside Monrovia came just one day after the 12,000-acre, American-managed rubber plantation, the biggest in the world, was reported captured by rebels of the National Patriotic Front. It could not immediately be ascertained whether the fighting, in which troops reportedly battled with rockets, mortars and automatic weapons, signified a planned government counteroffensive or a less organized clash.

{Agence France-Presse news agency, citing informed sources at the rebel-held port of Buchanan, said government troops had recaptured the rubber plantation.}

The reported fresh fighting appeared to deepen confusion over a military situation that has seen the rebels move nearly unopposed through the Liberian countryside for scores of miles, only to be slowed recently on the outskirts of the capital amid reports of internecine fighting among rebel factions.

The rebels, led by former government official Charles Taylor, are trying to overthrow the 10-year-old government of President Samuel Doe.

The six-month-old conflict, which has seen the rebels move from Nimba County on the southeastern border to within 35 miles of the capital and grow in strength from a handful of fighters to several thousand, has claimed an estimated 1,000 lives.

As the fighting has escalated, long-simmering ethnic animosities have flared openly. The strife has pitted members of Doe's ethnic group, the Krahns, against members of the Gio and Mano tribes who make up a majority of the rebels.

{The human rights group Amnesty International said government troops were carrying out "summary executions" of Gios and Manos, and that rebels had summarily slaughtered Krahns and members of the Mandingo tribe, whom they view as Doe sympathizers, AFP reported from London.}

The U.S. government, which has served as the chief benefactor of Doe's rule, elaborated plans to evacuate American citizens here Sunday.

The State Department again urged all Americans to leave Liberia immediately "due to the potential threat to lives." According to the U.S. Embassy, an estimated 1,200 to 2,000 U.S. citizens remain in Liberia. The government has contracted three flights Sunday of an Air Guinea Boeing 737 to carry a total of 360 U.S. passport holders to Ivory Coast.

There, a chartered Lockheed 1011 is to fly the Americans back to the United States. Meanwhile four U.S. military vessels and 2,300 U.S. Marines remain stationed off the Liberian coast to take part in emergency evacuation procedures should a need arise.

David K. Krecke, public affairs counselor at the U.S. Embassy, said a key benefit of the Sunday charter would be to help reduce the numbers of Americans in Liberia and leave fewer to worry about being caught in possible cross-fire.

Today's charter to Ivory Coast included Americans, Lebanese, Liberians and others.

At the U.S. Embassy today, about 150 persons showed up to register for the Sunday charters, for which the passengers will be charged about $1,200. According to observers, there was a great deal of confusion over who was eligible to fly. U.S. officials said only American passport holders are eligible, causing much distress to some Liberians whose families are divided between Liberian and American nationalities.

At Monrovia's Spriggs Payne Airport, hundreds of passengers clamored in the muggy heat for seats on several aircraft waiting on the tarmac. "Where are the Marines? Where are the peace-keepers?" shouted one angry man at a small group of journalists who arrived at the airport from neighboring Guinea this evening. "Why do you only send missionaries to us?"

Life in Monrovia seemed normal today, with many stores, cars and trucks operating despite skyrocketing prices for vital supplies and worsening shortages of fuel and food.