The Black Sea grain export initiative should be extended for a longer period and expanded, Ukrainian Deputy Prime Minister Oleksandr Kubrakov said on Thursday after talks finished in Turkey.

The United Nations and Turkey brokered the Black Sea export agreement last July to help tackle a global food crisis that has been exacerbated by Moscow's war in Ukraine, reported Reuters.

It allows the safe export of grains and fertilisers from three Ukrainian ports in condition of the Russian invasion.

"Negotiations in Istanbul on the functioning of the Grain Initiative have been completed," Kubrakov said on Facebook, without giving details of the outcome.

He said the talks would continue online.

"The Ukrainian delegation once again stressed that the Grain Initiative should be extended for a longer period and expanded. This will give predictability and confidence to both the global and Ukrainian markets."