It was not immediately clear whether the $1 billion was part of an existing $3 billion support package pledged last May by Saudi Arabia and the United Arab Emirates for Yemen's economy.
The internationally recognised government based in the south had seen its public finances worsen after the Houthi movement launched a series of attacks on terminals there that hampered oil exports, a key revenue source.
In November, the Arab Monetary Fund signed a $1 billion
agreement to support Yemen's economic reform programme.
The conflict has killed tens of thousands of people and left 80% of the population reliant on aid, with millions hungry.
Last month, the Aden-based government
raised the U.S. dollar exchange rate used to calculate customs duties on non-essential goods by 50% amid dollar shortages, sending prices to all-time highs.
On Tuesday, the rial was trading at 1,225 to the U.S. dollar on the black market in Aden, traders said.
Yemen has two rival central banks. The government has
resorted to money-printing to finance the deficit, but in
Houthi-held areas, where new notes are banned, the rate is
around 600 rials to the dollar.
(Reporting by Aziz El Yaakoubi, additional reporting by
Mohammed Alghobari in Aden; Editing by William Maclean and Ed
Osmond
)
