The aim is to create a safe corridor from Odesa on the Black Sea and possibly other ports to the Bosphorus so grain ships could reach the Mediterranean.
World food chiefs have warned that unless ports such as Odesa can be used for grain exports within weeks, acute food shortages could hit many countries, particularly in the developing world.
The operation would involve removing mines in the sea protecting the historic port of Odesa in southern Ukraine from Russian attack to allow ships to reach it.
However, Vladimir Putin has refused to guarantee that he would not use such a move to seek to launch an amphibious attack to try to seize the city.
So, the safe corridor would have to be protected in order for it to work and cargo ship operators to be able to get insurance.
It was not yet clear which nations, including America, are ready to take part in such a coalition-of-the-willing.
It could risk the Ukrainian war escalating into a broader conflict.
But without urgent action to end the Russian blockade of Ukraine’s ports, millions of people face hunger.
Bank of England governor Andrew Bailey sounded an “apocalyptic” warning last week about the risks of food shortages.
Earlier this month, David Beasley, head of the United Nations World Food Programme, pleaded with the Russian president to lift the blockade of Black Sea ports.
“Millions of people around the world will die because these ports are being blocked,” he stressed.
He emphasised that Odesa, which has come under repeated attack from Russian forces, and other ports needed to be working within the next two months to prevent catastrophe for Ukraine’s economy which is heavily focused on agriculture, recently accounting for just over 40 per cent of its exports.
The country’s grain harvest is due in around five to six weeks time and little silo capacity is believed to be available due to the impact of the war.
Ukraine is among the top five global exporters for several vital agricultural products, including corn, wheat and barley, according to the US government, as well as being the top exporter of both sunflower oil and meal.
However, it is far from clear whether a safe corridor could be established without the Kremlin’s consent.
A western official stressed: “I think the thing that we would have to rule out is any sense that this could be done without Russia’s permission.”
He added: “At the moment, there is minimal merchant vessel activity in the area, partly because it’s impossible to get insurance but also because of Russian naval activity and navigational warnings.
“In terms of operating through to Odesa and getting agreement to do that, clearly the Russians are dominating that area.
“It would require the permission of the Russians, some sort of of agreement to allow that to take place.”
He suggested that the Kremlin would ask for some form of “return on that arrangement” to allow shipping to operate out of Ukraine’s ports, such as easing sanctions.
Mr Putin’s navy is “someway off” Ukraine’s coast and “fearful of attack” after the sinking of its flagship Moskva missile cruiser.
But his military forces are thought to be controlling the area through precision missile capability from Sevastopol and the Crimea.
While land routes are available they are understood to be very hard to scale up to move large amounts of grain out of the country.