As a United Nations-led initiative to ship Ukrainian grain nears its expiration date next month, the government in Kyiv is stepping up its campaign against Russia to renew the deal on more favourable terms for the invaded country.

Russian ship inspectors working in Istanbul as part of UN-led teams are dragging their feet, leading to a queue of 140 inbound and outbound ships in the Bosphorus, two Ukrainian ministers said in a joint statement on Wednesday.