United Nations cultural agency UNESCO has been forced to suspend all its spending programmes until the end of the year after the United States withdrew its funding, its director general said Thursday.

In an address to UNESCO diplomats, Irina Bokova said the agency faces a $65 million (47 million euro) funding shortfall and would have to halt all of its activities, following a row with Washington over Palestinian membership.

"This deficit corresponds to the sum due from the United States for the year 2011. The United States have a habit of paying their contribution at the end of the year for reasons of their own budget caledar," she said.

"We will not receive this sum. We will therefore have to take radical measures, and we will need to take them now, at this general conference.

"I have suspended the entirety of our undertakings. I have suspended the execution of our programmes, during our review process, until the end of the year," she explained, promising her office would review the entire budget.

Last month, the United States and Israel pulled the plug on their UNESCO funding after members voted to admit Palestine as a full member, a move seen as a step towards its eventual recognition as a UN member state.

US legislation dating from the 1990s requires the US administration, Israel's staunchest ally, to withdraw funding from any UN agency that admits Palestine as a full member before a final peace deal is reached with Israel.

The Palestinians have also asked the UN Security Council for recognition, but the request is still being examined and Washington is all but sure to veto it.

Bokova said she hoped the year-end review would allow savings in UNESCO programmes -- which support cultural, educational and scientific projects around the world -- of around $35 million.

"But this won't be enough to resolve our problem," she warned in a speech to the 36th session of the UNESCO General Conference.

She went on to urge member states to increase their contributions to UNESCO's working fund in order to make up the shortfall caused by the US boycott.

"These are not decisions of choice, these are decisions of urgency," she said. "I do believe that we can pull through these difficulties, together -- for this, we must act now."