WASHINGTON - US Secretary of State Hillary Clinton and UN Secretary General Ban Ki-Moon on Thursday reviewed international efforts to compel Cote d'Ivoire's incumbent President Laurent Gbagbo to step aside immediately.

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In their meeting at the US State Department earlier the day, Clinton and Ban condemned the "unacceptable attacks" on UN peacekeepers in the West African state, department spokesman Mark Toner said in a statement.

The helicopters of United Nations Operation in Cote d'Ivoire and French troops are joining the attacks on Gbagbo's strongholds in the commercial capital of Abidjan by forces loyal to his rival Alassane Ouattara. Gbagbo has refused to cede power despite Ouattara's wide recognition as the winner in the Nov 28 presidential runoff.

Clinton and Ban also highlighted the need for the international community to "respond generously" to the increasing humanitarian needs in Cote d'Ivoire, Toner said.

He said that on the issue of UN reform, Clinton welcomed Ban's efforts to instill budget discipline and encouraged him to be "mindful of the need to seek efficiencies, to continue to emphasize a culture of transparency, and to further modernize the way they conduct their business."

Some Republican lawmakers are pressing for withholding of US payments to UN to force changes at the world body, but US ambassador Susan Rice told Congress that such a move would undermine US interests.

Ban also told top members of Senate Foreign Relations Committee that UN is doing what it can to reduce its budget and at the same time, "we need to have robust financial support from the United States."

As the single largest contributor, the United States contributes to 22 percent of UN's regular budget and 27 percent for its peacekeeping operations.