Senior U.N. and Russian officials met in Geneva on Wednesday to discuss Russian complaints that Western sanctions were impeding its grain and fertilizer exports despite a U.N.-brokered deal to boost Russian and Ukrainian shipments of the commodities.

The United Nations, Turkey, Ukraine and Russia agreed on July 22 on what was described by U.N. chief Antonio Guterres as a package deal to restart Ukraine's Black Sea grain and fertilizer exports and facilitate Russian shipments.

While the United States and others have stressed that Russian food and fertilizer is not subject to sanctions imposed over Moscow's Feb. 24 invasion of its neighbor, Russia has asserted there has been a chilling effect on its exports.

Senior U.N. trade official Rebeca Grynspan met with Russian Deputy Foreign Minister Sergei Vershinin for a "positive" discussion in Geneva on Wednesday, said U.N. spokesman Stephane Dujarric.

"The discussions are going on in a very constructive, professional level," he said. "The challenges are fairly clear, but I'm not going to get into the detail of what has been discussed around that table."

Russia's foreign minister, Sergei Lavrov, on Tuesday called for the removal of "logistic sanctions that prevent the free access of Russian grain and fertilisers to world markets."

Moscow's complaints come ahead of likely discussions aimed at extending the initial 120-day deal allowing Ukraine's Black Sea exports.

The aim of the package agreement was to help ease a global food crisis that the United Nations says was worsened by Russia's war in Ukraine and pushed tens of millions more people into hunger. Ukraine and Russia are both major wheat exporters.

Russian President Vladimir Putin on Wednesday said the accord was delivering grain, other food and fertiliser to the European Union and Turkey rather than to poor countries.

U.S. State Department deputy spokesperson Vedant Patel said on Wednesday that claims that Ukrainian grain was not going to countries in need were false. He said U.S. sanctions had always provided exemptions for food and fertilizer.

"The U.S. did not offer nor did it provide any sanctions relief in exchange for Russia's participation in the Black Sea Grain Initiative," Patel said. "We want to see food and fertilizer reach global markets and Russia must continue to live up to its commitments to the Black Sea Grain Initiative."

The United Nations has said the export deal is a commercial - not humanitarian - operation driven by the market.

"This initiative is about depressing global prices at the wholesale level and that's what we're seeing," Dujarric said.