The United States promised more military support for Ukraine, including drones, and is doing preliminary work on whether to send fighter aircraft, as fighting raged on in the east of the country five months into Russia's invasion.
Moscow and Kyiv signed a landmark deal on Friday to unblock grain exports from Black Sea ports. However, representatives declined to sit at the same table and avoided shaking hands at the agreement ceremony in Istanbul, reflecting wider enmity.
Ukrainian President Volodymyr Zelensky hailed Friday's agreement as unlocking around $10 billion worth of grain exports, needed to ease a food crisis.
But on the war, he said there could be no ceasefire unless lost territory was retaken.
"Freezing the conflict with the Russian Federation means a pause that gives the Russian Federation a break for rest," he told the Wall Street Journal.
"Society believes that all the territories must be liberated first, and then we can negotiate about what to do and how we could live in the centuries ahead."
There have been no breakthroughs on the front lines since Russian forces seized the last two Ukrainian-held cities in the eastern province of Luhansk in late June and early July.
Russian forces failed to establish control over Ukraine's second-biggest power plant at Vuhlehirska, northeast of Donetsk, and troops tried to advance west from the city of Lysychansk but were pushed back, the Ukrainian armed forces' general staff said.
In the southern town of Nikopol on the Dnipro river, continued Russian shelling killed at least one person, a Ukrainian official said on his Telegram channel.
"A 60-year-old woman died," said Oleksandr Vilkul, head of the military administration of Kryvyi Rih in central Ukraine.
The Russian attack on Nikopol in the south, target of more than 250 rockets in the past week, damaged 11 homes and farm buildings, cut off gas and water pipes, and destroyed a railway track, he added.
Russia's defence ministry did not immediately reply to a request for comment by Reuters outside regular hours.
Kyiv hopes that its gradually increasing supply of Western arms, such as US High Mobility Artillery Rocket System (HIMARS), will allow it to recapture territory.
Russia's defence ministry said on Friday its forces had destroyed four HIMARS systems between July 5 and Wednesday, refuted by the United States and Ukraine.
Reuters could not verify the battlefield reports.
The White House on Friday announced $270 million in fresh support for Kyiv, saying it was doing preliminary work on whether to send fighter aircraft, although such a move would not happen in the near term.
The Feb 24 invasion of Ukraine has caused Europe's biggest conflict since 1945, forcing millions to flee and turning entire cities to rubble. The Kremlin says it is engaged in a "special military operation" to demilitarise and "denazify" Ukraine. Kyiv and its allies say the war is an unprovoked act of aggression.
As the conflict drags on, credit rating firms Fitch and Scope downgraded Ukraine, two days after the country requested a debt payment freeze.
Friday's deal to allow certain exports to be shipped from Black Sea ports seeks to avert famine among tens of millions of people in poorer nations by delivering more wheat, sunflower oil, fertiliser and other products to world markets, including for humanitarian needs.
A blockade of Ukrainian ports by Russia's Black Sea fleet, trapping tens of millions of tonnes of grain and stranding many ships, has worsened global supply chain bottlenecks and, along with Western sanctions, stoked food and energy price inflation.
Moscow has denied responsibility for the crisis, blaming sanctions for slowing its own food and fertiliser exports and Ukraine for mining the approaches to its Black Sea ports.
A United Nations official said a separate pact signed on Friday would smooth such Russian exports and that the UN welcomed US and European Union clarifications that their sanctions would not apply to their shipment.
Senior UN officials 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, the officials said, although the word "ceasefire" was not in the agreement text.
"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," said UN Secretary General Antonio Guterres.
Russia's RIA news agency reported that Lithuania has lifted a ban on the rail transport of sanctioned goods into and out of the Russian territory of Kaliningrad, an enclave sandwiched between Poland and the Baltic state, cut off from the rest of Russia.
Lithuania had imposed the ban in June, triggering an outcry from Moscow and a promise of swift retaliation.