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 will sign a deal on Friday to reopen Ukrainian Black Sea ports for grain exports, Turkey said, raising hopes that an international food crisis aggravated by Russia's invasion can be eased.

Ukraine and Russia, both among the world's biggest exporters of food, did not immediately confirm Thursday's announcement by the office of the Turkish presidency. But in a late-night video address, Ukrainian President Volodymyr Zelenskiy hinted that his country's Black Sea ports could soon be unblocked.

The blockade by Russia's Black Sea fleet has worsened global supply chain disruptions and, along with Western sanctions imposed on Moscow, stoked high inflation in food and energy prices since Russian forces swept into Ukraine on Feb. 24.

Full details of the accord were not immediately released. It was due to be signed at 1330 GMT on Friday, Turkish President Tayyip Erdogan's office said.

U.N. Secretary-General Antonio Guterres, who would potentially co-sign any deal, was heading to Turkey. The Russian defence minister and Ukrainian infrastructure minister were also heading to Istanbul for the signing, sources said.

Zelenskiy, whose address focused mainly on Ukrainian forces' potential to make gains on the battlefield, said: "And tomorrow we also expect news for our state from Turkey - regarding the unblocking of our ports."

'PACKAGE' DEAL

Moscow has denied responsibility for the worsening food crisis, blaming instead a chilling effect from Western sanctions for slowing its own food and fertiliser exports and Ukraine for mining the approaches to its Black Sea ports.

The United Nations and Turkey have been working for two months to broker what Guterres called a "package" deal - to restore Ukraine's Black Sea grain exports while facilitating Russian grain and fertiliser shipments.

Russian Foreign Ministry spokesperson Maria Zakharova said the European Union had proposed relaxing some earlier sanctions to shore up global food security, and Moscow hoped this would create conditions for unhindered exports of grain and fertilisers.

Diplomats said last week details of the plan included Ukrainian vessels guiding grain ships through mined port waters, with Turkey overseeing inspections of ships to allay Russian concerns they might smuggle weapons to Ukraine.

Turkey, a NATO member that has good relations with Russia and Ukraine alike, controls the straits leading into the Black Sea and has acted as a mediator on the grain issue.

UKRAINE EYES TURNING THE TIDE

Zelenskiy met senior commanders on Thursday to discuss weapons supplies and intensifying attacks on Russians.

"(We) agreed that our forces have the strong potential to advance on the battlefield and inflict significant new losses on the occupiers," he said in his video address.

Kyiv hopes that gradually increasing supplies of precision, longer-range Western weaponry, such as U.S. High Mobility Artillery Rocket System (HIMARS), will allow it to counter-attack and recapture lost eastern and southern territories.

Russia's defence ministry said on Friday its forces had destroyed four HIMARS systems between July 5-20. Reuters could not verify the assertion.

Ukraine has accused the Russians of intensifying missile and rocket strikes on cities in recent weeks in a deliberate attempt to terrorise its population.

Cities and towns have been devastated by Russian bombardment during the conflict, with some far from front lines hit by missiles. Moscow denies deliberately firing on civilians and says all its targets are military.

However, there is a high chance of Russian longer-range weaponry missing their intended targets and causing civilian casualties because Moscow is increasingly using long-range air-defence systems to compensate for a shortage of ground-attack missiles, according to British military intelligence.

Such air-defence systems, tipped with smaller warheads to shoot down aircraft and missiles, are not likely to be able to penetrate hardened military structures on the ground and their crews will have little training for such missions, Britain's defence ministry said in an intelligence update on Friday.

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.

In its morning update, Ukraine's general staff said Russian forces backed by heavy artillery fire continued seeking gains towards the cities of Kramatorsk and Bakhmut and the Vuhlehirska thermal power plant in Donetsk province, but made no notable progress on the ground.

Ukrainian forces shelled Russian-held Donetsk city on Friday morning, the Russian state news agency TASS reported, quoting the self-proclaimed Donetsk People's Republic (DPR).

Ukrainian troops also destroyed bridges before retreating from the Luhansk city of Lysychansk, which is now impeding food deliveries, its acting Mayor Andrey Skory told TASS.

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.

The biggest conflict in Europe since World War Two has killed more than 5,000 people, driven more than 6 million out of Ukraine and left 8 million internally displaced, according to the United Nations.