He was speaking as the Security Council met to discuss a French resolution which would establish a force commanded and funded by the countries that volunteer to join it.
Despite reservations from some members, diplomats at the UN predicted final agreement on authorising a multi-national force before tonight.
Senior US officials scheduled a meeting for late last night to discuss a formal US response. Britain's UN Ambassador, John Weston, said the Government supported the idea of a force but would prefer it under UN command. After meeting with the council, Mr Boutros-Ghali said the refugees were facing "genocide by starvation" and that he had urged the ambassadors to move quickly.
He said a humanitarian crisis in eastern Zaire could not be averted "without the deployment, at least for a short period, of an international military force" and identified three options: a "well-equipped and well-supported" multinational force, sanctioned by the council but commanded by the nations contributing to it; a force raised and commanded by the United Nations; and an African peacekeeping mission.
"Given the need for urgent action if tens of thousands of lives are to be saved, time is of the essence," said Mr Boutros-Ghali. "This suggests that the best response to the current crisis would be the first option, by which member states with the necessary capacity would take the lead in putting together a multinational force." He said a UN force would take too long to organise and an African mission would need financial and logistical support.
Earlier, a statement issued during the French-British summit in Bordeaux said that the two countries had agreed to "co-ordinate their efforts closely, especially within the framework of the UN Security Council and the European Union" to ensure that humanitarian aid was able to reach refugees in Zaire, but it made no mention of any military contingent or any immediate emergency operation.
The wording of the statement suggested that all further action would be referred to international organisations, and would therefore take time. French sources later conceded that France had "experienced difficulty" in persuading other countries of direct intervention with a military element. Earlier, it had been made clear that France would not take any unilateral military action.
The Foreign Secretary, Malcolm Rifkind, said later that Britain did not "rule out" a "military dimension" if this was required to ensure the provision of aid and food. He noted, however, that there were many questions still to be answered, including: "What is the best way of ensuring that the suffering can be ameliorated ... does that require a military contribution from the international community? If it does, should the UK be involved?"
He emphasised that a political solution "covering Rwanda, Burundi and that part of Zaire" was also required, but that this would take some time to work out and was primarily a matter for the countries of the region. "If the international community can help," he added, then it had an obligation to do so.
The joint French-British statement represented a setback for France, which had obtained the agreement of Spain to the dispatch of a multilateral military contingent to Zaire at the French-Spanish summit in Marseilles earlier this week.
All official British statements in recent days have stressed the complexity of the political situation in Zaire and the need to have the agreement of all countries in the region before action was taken involving troops. How difficult this could be to obtain became apparent yesterday, when Rwanda said it would accept a "fully neutral" European and African force, but implied that French and Belgian participation would not be welcome.
France is currently sheltering President Mobutu of Zaire, who arrived from Switzerland at the beginning of the week and is now staying at his villa on the Riviera.
France also revealed yesterday that its invitation to the US to join a multinational effort had been met with a list of 30 questions. The French foreign minister, Herve de Charette, said France had sent back "precise replies" on all points.