By Michelle Nichols

UNITED NATIONS (Reuters) - U.S. Secretary of State Mike Pompeo told countries at the United Nations on Saturday to "pick a side" on Venezuela, urging them to back Venezuelan opposition leader Juan Guaido and calling for free and fair elections as soon as possible.

Pompeo was addressing the 15-member U.N. Security Council, which met at his request after Washington and a string of countries in the region recognized Guaido as head of state and urged Venezuelan President Nicolas Maduro to step down.

"Now it is time for every other nation to pick a side ... Either you stand with the forces of freedom, or you're in league with Maduro and his mayhem," Pompeo told the council. "We call on all members of the Security Council to support Venezuela's democratic transition and interim President Guaido's role."

Guaido, who took the helm of the National Assembly on Jan. 5, proclaimed himself interim president on Wednesday though Maduro, who has led the oil-rich nation since 2013 and has the support of the armed forces, has refused to stand down.

Maduro cruised to re-election in May last year amid low turnout and allegations of vote-buying by the government. The domestic opposition, the United States and right leaning Latin American governments declined to recognize the result of the vote.

Under Maduro, Venezuela has sunk into turmoil with food shortages and daily protests amid an economic and political crisis that has sparked mass emigration and inflation that is seen rising to 10 million percent this year.

Britain, Germany, France, Spain and Belgium all said on Saturday they would recognize Guaido as interim president unless Maduro called fresh elections within eight days.

"Europe is giving us eight days? Where do you get that you have the power to establish a deadline or an ultimatum to a sovereign people," Venezuela's Foreign Minister Jorge Arreaza told the Security Council. "It's almost childlike."

Arreaza said Maduro's government still hopes to establish communication and dialogue with U.S. President Donald Trump's administration. "That offer stands," he told the council.

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Russia's U.N. Ambassador Vassily Nebenzia called the eight day ultimatum "absurd." Moscow opposes the U.S. efforts and has accused Washington of backing a coup attempt, placing Venezuela at the heart of a growing geopolitical duel.

"This is not about foreign intervention in Venezuela," former U.S. diplomat Elliott Abrams, who Pompeo named on Friday to lead U.S. efforts on Venezuela, told the council.

Russia failed in a bid to stop Saturday's Security Council meeting. China, South Africa and Equatorial Guinea voted with Moscow to block the meeting, while nine countries voted in favor of the meeting. Ivory Coast and Indonesia abstained.

"We strongly condemn those who are pushing the Venezuelan society to the edge of a bloodbath. The U.S. are painting a picture of a confrontation between the Maduro regime and the people of Venezuela. This picture is far from reality," Nebenzia told the Security Council.

Russia, China, South Africa and Equatorial Guinea also blocked a U.S. push for a U.N. Security Council statement expressing full support for Venezuela's National Assembly as the country's "only democratically elected institution."

"China does not interfere in other countries internal affairs. We hope the country that accuses others can do likewise itself," said China's U.N. Ambassador Ma Zhaoxu, referring to the United States.

The United States has signaled it was ready to step up economic measures to try to drive Maduro from power.

Pompeo told reporters on Saturday that he hopes countries "will ensure that they disconnect their financial systems from the Maduro regime and allow assets that belong to the Venezuelan people to go to the rightful governors of that state."

(Additional reporting by Humeyra Pamuk in Washington, Editing by William Maclean and Diane Craft)