Russian President Vladimir Putin said Wednesday the grain leaving Ukrainian ports after a blockade that fuelled a global food crisis was mostly reaching Europe instead of developing nations and questioned the merits of the deal.

The United Nations and Turkey brokered an agreement with Moscow and Kyiv -- the first between the two since the February launch of Russia's military campaign -- restoring frozen Ukrainian grain deliveries across the Black Sea.

But Moscow has voiced increasing frustration with how the agreement was being applied.

An amendment to the deal also allowed Russia to get open access to fertiliser shipments and have some economic sanctions lifted to allow it to export its own grain.

The UN hailed the agreement as the world's best chance to ease an acute global food crisis stoked by the Black Sea grain blockade.

Putin told an economic forum in Russia's Pacific port of Vladivostok that the deal was helping richer European countries at the expense of the developing world.

"Almost all the grain exported from Ukraine is sent not to the poorest developing countries, but to EU countries," he said.

Both Ukraine and Russia are two of the biggest exporters of wheat and other grain.

Putin accused European countries of acting as "colonialists" and said they "once again simply deceived developing countries".

"With this approach, the scale of food problems in the world will only grow," Putin said.

"Maybe we should think about limiting the export of grain and other produce along this route?" Putin said.

The July agreement is valid for 120 days and may be automatically renewed without further negotiations.

But it requires both Moscow and Kyiv to sign off on a renewal.

Official data collected by a joint centre in Istanbul monitoring the deal's implementation showed 30 percent of the grain reaching "low and lower-middle income countries".

Data compiled as of Wednesday and released to AFP showed Turkey receiving the largest share of the grain -- 20 percent -- followed by Spain (15 percent) and Egypt (10 percent).

But much of the grain that reaches Turkey and some other destinations is then re-sold under commercial agreements not monitored by the Istanbul centre.

A separate famine relief effort spearheaded by the UN's World Food Programme (WFP) is focused on delivering wheat and maize to Africa and other parts of the world suffering shortages.

The first UN-chartered vessel docked in Djibouti on August 30 as part of a response to the drought gripping the Horn of Africa.

A second UN ship reached Turkey last week. The wheat is now being milled into flour and will then be loaded onto a new vessel and sent to Yemen at an undisclosed date.

"I hope that the situation will improve somehow," said Putin.

"We will continue insisting that this whole affair with the export of grain and our food be directed primarily to developing markets."