United Nations, May 6 : The world body is working toward the extension of the Black Sea Grain Initiative, and asks all parties concerned to engage constructively, a UN spokesman has said. The Joint Coordination Centre (JCC) has not reached agreement to authorise new vessels to participate in the initiative, which allows the export of Ukrainian grain and other agricultural products from Black Sea ports. The JCC continues its daily inspection work on the previously authorised vessels, Farhan Haq, deputy spokesman for UN Secretary-General Antonio Guterres, was quoted by Xinhua news agency as saying on Friday. The UN chief has communicated to all parties his proposal on the way forward aimed at the improvement, extension and expansion of the initiative, taking into account positions expressed by the parties, said the spokesman. "We urge all parties to continue their discussions, overcome operational challenges and work toward the full implementation and continuation of the initiative." UN representatives will be participating in a technical meeting convened by the Turkish government on the initiative, in preparation for a senior-level meeting taking place next week in Istanbul, said Haq. "So we're looking forward to constructive and frank discussions with all sides, with the aim to overcome challenges and work toward the continuation and full implementation of the initiative." All the parties -- Russia, Ukraine, the United Nations, and Turkey -- will be represented at next week's senior-level meeting. But the names of the participants are still to be determined, he told a daily press briefing. Head of the UN Conference on Trade and Development, Rebeca Grynspan, travelled to Moscow on Friday as part of the ongoing consultations with senior Russian officials regarding the world body's engagement to facilitate the unimpeded export of Russian food and fertiliser, including ammonia, to global markets, said Haq. The memorandum of understanding between Russia and the United Nations on the facilitation of exports of Russian food and fertiliser is a parallel agreement with the Black Sea Grain Initiative. While the exports of Ukrainian grain have made strides, Russia has constantly expressed displeasure with the lack of progress in the facilitation of exports of Russian food and fertiliser. Grynspan met with Russian Deputy Foreign Minister Sergei Vershinin, relaying the strong commitment of the UN secretary-general to the full implementation of the memorandum of understanding, said Haq. Last week, Guterres presented Russian Foreign Minister Sergei Lavrov with a letter to Russian President Vladimir Putin, outlining his proposal for the improvement, extension and expansion of the Black Sea Grain Initiative. Haq said Friday that Guterres has not received any formal response from Putin. The Black Sea Grain Initiative was signed separately by Russia and Ukraine in Istanbul with Turkey and the United Nations on July 22, 2022. The deal, initially in effect for 120 days, was extended in mid-November 2022 for another 120 days till March 18, 2023. At that point, Russia only agreed to extend the deal for a further 60 days, till May 18. /IANS