"I am particularly concerned about the recent decline of commercial food imports through the Red Sea ports. Pressure on the currency and a liquidity crisis in the Yemeni banking system make imports less viable for traders," Mark Lowcock, UN emergency relief coordinator, said in a statement.

Confidence among commercial shippers has eroded due to delays, "including as a result of inspections undertaken by the Saudi-led coalition after these vessels have been cleared by UNVIM," he said, referring to the UN verification mechanism.

Copyright Reuters, 2018