U.S. State Department spokesperson Ned Price said on Monday it was a "critical moment" in negotiations on the UN-brokered Black Sea Grain Initiative, which Washington hopes will be extended before it expires on March 18.
Russia has suggested extending the deal, which allows the safe export of grain from Ukraine's Black Sea ports, but only for a period of 60 days.
Price said the world needs the initiative, which he said allowed grain shipments to developing countries and helped bring down food prices.
"This is a critical instrument at a critical time," Price said.
(Reporting by Humeyra Pamuk, Kanishka Singh and Simon Lewis; Editing by Leslie Adler)