Three UN officials urged the US to reverse its decision to designate Yemen's Houthi rebels as terrorists, saying the move could lead to a backlash that causes more food shortages in the conflict-blighted country.
US Secretary of State Mike Pompeo on Sunday said the Iran-backed Houthis would be classified as a terrorist group, freezing any US-related assets and banning Americans from offering any support to the movement.
The move comes into effect on January 19, the day before President Donald Trump hands over control of the White House to president-elect Joe Biden.
The new administration, however, could revoke the designation.
Yemen's internationally recognised government welcomed the announcement to put pressure on the Iran-backed Houthi movement, which has blocked the distribution of humanitarian aid.
Several regional countries also welcomed the move, as did the Gulf Co-operation Council.
The Secretary General of the GCC, Nayef Al Hajraf, called the move “a necessary step that is consistent with the demands of the Yemeni government".
UN officials fear any backlash from the group, which controls Sanaa and other parts of the north, could worsen food shortages throughout Yemen.
UN aid chief Mark Lowcock told the Security Council on Thursday that Washington’s decision was discouraging suppliers, banks and shipping companies from operating in Yemen.
Mr Lowcock said the threat of US sanctions was reducing imports and causing “famine on a scale that we have not seen for nearly 40 years".
“Some suppliers, banks, shippers and insurers are ringing up their Yemeni partners and saying they now plan to walk away from Yemen altogether,” he told an online council meeting.
“They fear being accidentally or otherwise caught up in US regulatory action that would put them out of business or into jail.”
Locals were stockpiling food before the measures come into effect.
“Yemenis are crowding into markets and shops to stockpile whatever they can afford,” Mr Lowcock said.
His comments were echoed by Martin Griffiths, the UN envoy to Yemen, and David Beasley, head of the Nobel Peace Prize-winning World Food Programme.
“This designation … needs to be reversed,” Mr Beasley said. “It's going to be catastrophic."
Mr Griffiths said the designation cast a shadow on efforts for a peace deal between the Houthis and the government of President Abdrabu Mansur Hadi, which the rebels drove from the capital Sanaa in 2014.