Talks are continuing with Russia to increase grain shipments from Ukraine’s Black Sea ports despite Moscow’s warnings that damage to a key ammonia pipeline jeopardises the longer-term success of the deal, the head of the operation said on Monday.

Abdullah Dashti, who was appointed in December as the coordinator for the United Nations’ Black Sea Grain Initiative (BSGI), told a conference in London that his team was working “day and night” to resolve the latest in a litany of problems that have affected the initiative.