The Kremlin said on Monday that talks with the United Nations last week on a deal safeguarding the shipment of grain from Ukrainian ports had been "fairly constructive", raising hopes that it can be rolled over smoothly.

Senior U.N. officials met a Russian delegation in Geneva on Friday to discuss Moscow's grievances about the Black Sea grain initiative, which has since August lifted a Russian blockade of the seaports of one of the world's main grain exporters.

"There were talks with the U.N. last week, fairly constructive talks. We have our interest in this deal, which was originally part of the whole mechanism of the deal," Kremlin spokesman Dmitry Peskov told reporters.

Russia has been demanding unhindered access to world markets for its own food and fertiliser exports in return for agreeing to a rollover of the Black Sea deal, which is due for renewal on Nov. 19. Moscow has indicated that it could quit the deal if progress is not made on its concerns.

"We are actually still a week away from the extension date, so work is ongoing," Peskov added.

Russia is the world's largest wheat exporter and a major supplier of fertilisers to global markets.

Ukraine's main export route, through its Black Sea ports, was blocked between late February, when Moscow sent armed forces into its neighbour's territory, and July, when the U.N.-brokered deal was signed.

Since then, Moscow has repeatedly complained that its shipments of grain and fertilisers, though not directly targeted by Western sanctions, are constrained because the sanctions make it harder for exporters to process payments or to obtain vessels, insurance and access to ports.

The United Nations said on Friday that the participants "remain engaged in the implementation of the Black Sea Grain Initiative and held constructive discussions on its continuation".

(Reporting by Reuters; Editing by David Goodman and Kevin Liffey)