The UN warned Wednesday that agreements to enable grain shipments from war-torn Ukraine, desperately needed to ward off hunger in poor countries, were in "difficult territory".
The hard-won Black Sea Grain Initiative was brokered by the UN and Turkey last July. It was renewed a first time in November and is up for renewal again on March 18.
"I think we're in slightly more difficult territory at the moment," UN humanitarian chief Martin Griffiths told reporters.
He insisted though that the arguments for continuing were "conclusive and persuasive," stressing that "the Global South ... needs that operation to continue."
Ukraine is one of the world's top cereal producers.
After Russia launched its invasion nearly a year ago, 20 million tonnes of grain were blocked in its ports until a safe passage deal was agreed.
Nearly 20 million tonnes of cereal have been exported since then, said Griffiths, insisting: "We don't need it stopped in the middle of March."
"I hope and I believe, actually, that it will be extended. That is because it is an obvious case for international humanitarian security."
One complication is that the initiative was agreed in parallel with a deal aimed at smoothing the way for exports of Russian fertiliser.
The memorandum of understanding between the UN and Russia -- due to last three years -- sought to ensure that sanctions imposed on Moscow over the war did not block such exports, which are also seen as vital to the world food supply.
But Moscow has repeatedly complained that the deal is not being respected.
The last time the Black Sea Grain Initiative was up for renewal, Russia briefly threatened to block it over the fertiliser impasse.
Griffiths acknowledged that it was "much more complicated in many ways to make (the fertiliser deal) work."
"But it is important that it does work," he said, insisting that freeing up fertiliser exports is "of the highest priority."
Griffiths said a lot of work had gone into making the deals work, admitting though that there was "a lot more to be done on that front."
