The agreement to export grain through a safe shipping lane in the Black Sea should be extended and scaled up when the current deal finishes this week, according to the UN and the scheme’s Western backers. The 120-day programme, brokered by Turkey and the UN, is due to end on Saturday amid efforts to persuade Russia to back the extension to ease global hunger and keep food prices down.

“We demonstrate our call on all countries to demonstrate their support for the Black Sea Grain Initiative,” the US, UK and European Union said in a joint statement. “We call on the parties to the initiative to extend its terms and scale up its operations to meet the evident demand.”

Any extension relies on Moscow, which briefly withdrew its support for the scheme last month after drone attacks on several Russian warships. It returned to the humanitarian scheme after assurances that the shipping corridor would not be used for military purposes.

The UN said all sides are still discussing the deal to extend Ukraine grain exports but nothing has been decided. Russia said it would give its decision at an “appropriate” time. Russia has expressed anger that it has been unable to export fertilizer owing to the indirect impact of sanctions.

UN secretary general Antonio Guterres told G20 leaders, minus Vladimir Putin, meeting in Bali, Indonesia that many of the obstacles to allowing the free flow of Russian food and fertilizers to global markets have been removed. “We are working non-stop to resolve all remaining issues, chiefly around payments, and to renew the Black Sea Grain Initiative,” he said. There is already a threat of a “raging food catastrophe” because of shortages, he added.

The UN-led Joint Coordination Center has reported a backlog of 60 bulk carriers waiting to load cargo as Ukrainian authorities continue to blame Russia for holding up inspections. Eight more vessels loaded with wheat, barley, corn and sunflower meal are awaiting inspection in Turkish waters. A further four were reported on Monday as being ready to depart Ukraine.