Yemen's central bank has complained to its allies in a Saudi-led military coalition about a lack of cash deliveries needed to pay salaries, in a sign of the government's struggle to keep the war-torn country's economy afloat.
There are two opposing central banks in Yemen - an internationally recognized one in the southern city of Aden and another in the capital Sanaa in territory run by the government's foes in the armed Houthi movement.
Both suffer from depleted reserves but play a key role in mitigating widespread famine and disease, after two years of fighting, by paying some public sector salaries.
But the Aden bank said in a statement late on Saturday that the Saudi-led coalition had not given landing permits for air shipments of cash 13 times for unknown reasons - in a rare airing of a grievance by the government to its main backer.
"The (bank) faces extreme difficulties ... because of the hindrance in delivering these funds by air to Aden airport by the coalition for unknown reasons," the bank said.
"This creates dangerous strangulation for the Yemeni economy in providing liquidity for the crisis," it added. It did not say which currency the deliveries would be.
Saudi Arabia and its mostly Gulf Arab allies control Yemen's air space, a measure they say aims to prevent Iran delivering arms shipments to the Houthis - a charge the Houthis deny.
A spokesman for the coalition did not immediately respond to a Reuters request for comment.
Forces loyal to President Abd-Rabbu Mansour Hadi wrested Aden and several southern provinces from the Houthis in the summer of 2015 but have struggled to impose stability and the government still operates mostly from exile in the Saudi capital Riyadh.
Militants and gunmen continue to operate in many southern areas, and banks in Aden closed for three days in protest last month after a spate of armed robberies.