The United Arab Emirates is barring ships carrying some 170 billion Yemeni rials (£490 million) from entering the southern port of Aden, officials in Yemen have said.
They said the money is meant for the salaries of government employees who have not been paid for over a year.
There was no immediate comment from the UAE.
Aden is under the control of the UAE, a key partner in the Saudi-led coalition fighting the Shiite Houthi rebels, who control most of northern Yemen, including the capital, Sanaa.
The coalition is fighting on the side of President Abed Rabbo Mansour Hadi’s government, but the UAE has long been at odds with Mr Hadi.