A tanker truck drives past Ukrainian border guard boats docked in the Black Sea port of Odessa, Ukraine November 26, 2018.
A tanker truck drives past Ukrainian border guard boats docked in the Black Sea port of Odessa, Ukraine November 26, 2018. Reuters / VOLOKIN YEVGENY

Russia and Ukraine signed a landmark deal on Friday to reopen Ukrainian Black Sea ports for grain exports, raising hopes that an international food crisis aggravated by the Russian invasion can be eased.

The accord crowned two months of talks brokered by the United Nations and Turkey, a NATO member that has good relations with both Russia and Ukraine and controls the straits leading into the Black Sea.

Speaking at the signing ceremony in Istanbul, U.N. Secretary General Antonio Guterres said the deal opens the way to significant volumes of commercial food exports from three key Ukrainian ports - Odesa, Chernomorsk and Yuzhny.

"Today, there is a beacon on the Black Sea. A beacon of hope..., possibility...and relief in a world that needs it more than ever," Guterres told the gathering.

But fighting raged on unabated in Ukraine's east and, underlining the enmity and mistrust driving the worst conflict in Europe since World War Two, Russian and Ukrainian representatives declined to sit at the same table and avoided shaking hands at the ceremony.

A blockade of Ukrainian ports by Russia's Black Sea fleet, trapping tens of millions of tonnes of grain in silos and stranding many ships, has worsened global supply chain bottlenecks and, along with sweeping Western sanctions, stoked galloping inflation in food and energy prices around the world.

Moscow has denied responsibility for the worsening food crisis, blaming instead sanctions for slowing its own food and fertilizer exports and Ukraine for mining the approaches to its Black Sea ports.

A U.N. official said a separate pact signed on Friday would smooth such Russian exports and that the United Nations welcomed U.S. and European Union clarifications that their sanctions would not apply to their shipment.

Canadian Prime Minister Justin Trudeau said Western nations would be watching closely to ensure the deal did not put Ukraine at risk of being further invaded by Russia.

"The G7 is working closely with partners like Turkey and others to ensure that we can get that grain out of Ukraine and to places around the world where it's needed without putting at risk Ukraine's sovereignty and protection," Trudeau said.

SAFE PASSAGE

Speaking in Istanbul, Russian Defence Minister Sergei Shoigu said Moscow would not seek to take advantage of the de-mining of Ukraine's ports.

"Russia has taken on the obligations that are clearly spelled out in this document. We will not take advantage of the fact that the ports will be cleared and opened," Shoigu said on the Rossiya-24 state TV channel.

Ukraine's infrastructure minister Oleksandr Kubrakov also said that Kyiv does not see a risk of Russian ships attacking through Ukrainian ports.

Senior U.N. officials, briefing reporters on Friday, said the deal was expected to be fully operational in a few weeks and would restore grain shipments from the three reopened ports to pre-war levels of 5 million tonnes a month.

Safe passage into and out of the ports would be guaranteed in what one official called a "de facto ceasefire" for the ships and facilities covered, they said, although the word "ceasefire" was not in the agreement text.

Though Ukraine has mined nearby offshore areas as part of its defences against Russia's five-month-old invasion, Ukrainian pilots would guide ships along safe channels in its territorial waters, they said.

Monitored by a Joint Coordination Center based in Istanbul, the ships would then transit the Black Sea to Turkey's Bosphorus strait and proceed to world markets, U.N. officials said.

The overall objective is to help avert famine among tens of millions of people in poorer nations by injecting more wheat, sunflower oil, fertilizer and other products into world markets including for humanitarian needs, partly at lower prices.

The United States welcomed the deal and said it was focusing on holding Russia accountable for implementing it.

TURNING THE BATTLEFIELD TIDE?

Ukrainian President Volodomyr Zelenskiy met senior commanders on Thursday and said Kyiv's forces, now increasingly armed with precision, longer-range Western weaponry, had strong potential to turn the tide on the battlefield.

The United States believes Russia's military is sustaining hundreds of casualties a day, a senior U.S. defense official said on Friday. The official said Washington also believed that Ukraine had destroyed more than 100 "high-value" Russian targets in Ukraine, including command posts and air-defence sites.

There have been no major breakthroughs on front lines since Russian forces seized the last two Ukrainian-held cities in eastern Luhansk province in late June and early July.

Russian forces are now focused on capturing all of neighbouring Donetsk province on behalf of separatist proxies who have declared two breakaway mini-states covering the wider industrialised Donbas region.

Kyiv hopes that its gradually increasing supply of Western arms, such as U.S. High Mobility Artillery Rocket System (HIMARS), will allow it to recapture lost territories.

Russia's defence ministry said on Friday its forces had destroyed four HIMARS systems between July 5-20. Kyiv denied the claims, calling them "fakes" meant to sap Western support for Ukraine. Reuters could not verify the assertions.

Russia says it is waging a "special military operation" to demilitarise its neighbour and rid it of dangerous nationalists.

Kyiv and the West say Russia is mounting an imperialist campaign to reconquer a pro-Western neighbour that broke free of Moscow's rule when the Soviet Union collapsed in 1991.