UNITED NATIONS, July 27 (Reuters) - United Nations Secretary-General Antonio Guterres warned on Thursday that a "handful of donations" won't correct the dramatic impact of the end of a deal that had allowed the safe Black Sea export of Ukraine grain for the past year.

Global wheat prices have spiked about 10% in the past 10 days after Russia quit the pact - brokered by the United Nations and Turkey in July 2022 - and began targeting Ukrainian ports and grain infrastructure on the Black Sea and Danube River.

"It is clear that when taking out of the market millions and millions of tonnes of grains it is clear that ... will lead to higher prices," Guterres told reporters. "So it's not with a handful of donations to some countries that we correct this dramatic impact that affects everybody, everywhere."

Russian President Vladimir Putin on Thursday told African leaders he would gift them tens of thousands of tons of grain within months despite Western sanctions, which he said made it harder for Moscow to export its grain and fertilisers.

Russia's grain and fertilizer exports are not subject to Western sanctions, but Moscow said restrictions on payments, logistics and insurance have been a barrier to shipments. It has a list of demands it wants met to improve its own exports.

Under the Black Sea grain deal, which aimed to combat a global food crisis worsened by Russia's February 2022 invasion of Ukraine, nearly 33 million tonnes of Ukraine grain was exported. Ukraine and Russia are both leading grain exporters.

While global wheat prices are about half the record high hit in early March 2022 after Russia's invasion, Guterres said any increase now would be "paid by everybody, everywhere - and namely by developing countries and by the vulnerable people in middle-income and even developed countries."