MOSCOW (Reuters) -Russia said on Wednesday the United Nations had three months to implement the terms of a memorandum that would facilitate Russian agricultural exports if it wanted Moscow to resume talks about allowing Ukrainian grain exports to restart.

Russia said on Monday it was halting participation in a year-old U.N.-brokered deal that let Ukraine export grain through the Black Sea, complaining that promises to facilitate its own shipments of food and fertilisers had not been kept.

The Black Sea deal was brokered by the U.N. and Turkey in July last year to help combat a global food crisis and overcome additional obstacles thrown up after Russia sent troops into Ukraine.

Kyiv and Moscow are among the world's top grain exporters.

Russia's withdrawal meant that the related pact to assist its own grain and fertiliser exports was also terminated, U.N. Secretary-General Antonio Guterres signalled at the time.

Russian Foreign Ministry spokeswoman Maria Zakharova said the onus was now on the United Nations to implement the Russian deal if it wanted Moscow to return to wider talks about it helping revive Ukrainian exports.

"The Russia-United Nations Memorandum itself states, and I'll quote...that the agreement will be in force for three years, and in case one of the parties intends to terminate it (either Russia or the UN), it must give three months' notice. We have given notice," Zakharova told Radio Sputnik on Wednesday.

"Accordingly, the UN still has three months to achieve concrete results. Therefore, people should not run to the microphones at the UN Secretariat, but use these three months to achieve concrete results. If there are concrete results, we will return to the discussion of this (wider) issue."