United Nations, Aug 17 (IANS): More than half a million tonnes of grain have been exported from Ukraine across the Black Sea since the beginning of August, the UN said.

Since Ukraine, Russia, Turkey and the UN agreed to open the Black Sea route at the end of July, 36 passages have been approved, the UN said on Tuesday, adding that 21 ships left Ukraine for the Bosporus and 15 moved through the strait in the direction of the war-torn country.

A total of 27 freighters were searched in Turkey as stipulated by the agreement, reports dpa news agency.

It is estimated that more than 20 million tonnes of grain products are stuck in Ukraine since Russia launched its war on February 24 and blockaded the country's ports.

More than a quarter of all outgoing grain shiploads have so far been destined for Turkey, 22 per cent for Iran and South Korea, 8 per cent for China and 6 per cent for Ireland, the UN said.

On Tuesday, a first freighter on behalf of the UN set off for Djibouti in East Africa.

So far, a little more than 560,000 tonnes of grain products have been exported, namely corn, sunflower meal and wheat.

At the end of July, the warring parties concluded agreements with Turkey and the UN to guarantee a transport route for ships carrying agricultural goods from the war zone.

The UN fears food shortages and hunger in poor parts of the world if Ukraine fails as a major grain supplier.