Russian president Vladimir Putin warned on Saturday that Ukrainian statehood is in jeopardy and likened the West’s sanctions on Russia to “declaring war,” while a promised ceasefire in the port city of Mariupol collapsed amid scenes of terror in the besieged town.

With the Kremlin’s rhetoric growing fiercer and a reprieve from fighting dissolving, Russian troops continued to shell encircled cities and the number of Ukrainians forced from their country grew to 1.4 million.

Bereft mothers mourned dead children, wounded soldiers were fitted with tourniquets and doctors worked by the light of their mobile phones as bleakness and desperation pervaded.

Putin continued to pin the blame for all of it squarely on the Ukrainian leadership and attacked their resistance to the invasion.

“If they continue to do what they are doing, they are calling into question the future of Ukrainian statehood,” he said. “And if this happens, it will be entirely on their conscience.”

He also hit out at Western sanctions that have crippled Russia’s economy and sent the value of its currency tumbling.

“These sanctions that are being imposed, they are akin to declaring war,” he said during a televised meeting with flight attendants from Russian airline Aeroflot.

“But thank God, we haven’t got there yet.”

Ten days after Russian forces invaded, the struggle to enforce the temporary ceasefire in Mariupol and the eastern city of Volnovakha showed the fragility of efforts to stop the fighting across Ukraine.

Ukrainian officials said Russian artillery fire and airstrikes had prevented residents from leaving before the agreed evacuations got under way. Putin accused Ukraine of sabotaging the effort.

The third round of talks since Russia invaded will take place Monday, Davyd Arakhamia, a member of the Ukrainian delegation, said on Saturday.

He did not give further details, including where they will take place. The last round was held in Belarus.

Earlier, the Russian defence ministry said it had agreed with Ukraine on evacuation routes out of the two cities.

Before the announcement, Russia’s days-long assault had caused growing misery in Mariupol, where AP journalists witnessed doctors make unsuccessful attempts to save the lives of wounded children, pharmacies ran bare and hundreds of thousands of people faced food and water shortages in freezing weather.

In comments carried on Ukrainian television, Mariupol mayor Vadym Boychenko said thousands of residents had gathered for safe passage out of the city when shelling began Saturday.

“We value the life of every inhabitant of Mariupol and we cannot risk it, so we stopped the evacuation,” he said.

In recent days, Ukraine had urged Moscow to create humanitarian corridors to allow children, women and the older adults to flee the fighting, calling them “question number one”.

Ukrainian president Volodymyr Zelenskyy held out the possibility that talks with Russia could result in a sustained, if limited ceasefire on Saturday.

Elsewhere in the country, Ukrainian forces were holding key cities in central and south-eastern Ukraine, while the Russians were trying to keep Kharkiv, Mykolaiv, Chernihiv and Sumy encircled, he said.

Russian foreign minister Sergey Lavrov on Saturday said Russia was ready for a third round of talks on that and other issues, but he asserted that “the Ukrainian side, the most interested side here, it would seem, is constantly making up various pretexts to delay the beginning of another meeting”.

Diplomatic efforts continued as US secretary of state Antony Blinken arrived in Poland to meet the prime minister and foreign minister, a day after attending a Nato meeting in Brussels in which the alliance pledged to step up support for eastern flank members.

In Moscow, Israeli prime minister Naftali Bennett was meeting Putin at the Kremlin.

Israel maintains good relations with both Russia and Ukraine, and Bennett has offered to act as an intermediary in the conflict. No details of Saturday’s meeting have yet emerged.

In the wake of Western sanctions, Aeroflot, Russia’s flagship state-owned airline, announced that it plans to halt all international flights. except to Belarus, starting on Tuesday.

At least 351 civilians have been confirmed killed since Russia’s invasion of Ukraine on February 24, but the true number is probably much higher, the UN human rights office has said.

Mr Zelensky said on Saturday that that 10,000 Russian troops had died in the war, a claim that could not be independently verified.

“We’re inflicting losses on the occupants they could not see in their worst nightmare,” the Ukrainian leader said.

The Russian military, which does not offer regular updates on casualties, said Wednesday that 498 of its troops had been killed.

Ukraine’s military might is vastly outmatched by Russia’s, but its military and volunteer forces have fought back with fierce tenacity since the invasion. Even in cities that have fallen to the Russians, there were signs of resistance.

Onlookers in Chernihiv cheered as they watched a Russian military plane fall from the sky and crash, according to video released Saturday by the Ukrainian government.

In Kherson, hundreds of people protested against the invasion, shouting: “Go home.”

Mr Zelensky encouraged protests that drew thousands to the streets in Russian-occupied cities.

“Go on the offensive,” he urged. “You should take to the streets, You should fight.”

A vast Russian armoured column threatening Ukraine’s capital remained stalled outside Kyiv.

Ukrainian presidential adviser Oleksiy Arestovich said the military situation was more quiet overall on Saturday and Russian forces “have not taken active actions since the morning”.

While the shelling in Mariupol showed Russia’s determination to cut Ukraine off from access to the Black Sea and the Sea of Azov, further damaging the country’s economy, it was Putin who was most on the offensive with his comments warning that a no fly zone would be considered a hostile act.

Nato has said it has no plans to implement such a no-fly zone, which would bar all unauthorised aircraft from flying over Ukraine. Western officials have said a main reason is a desire to not widen the war beyond Ukraine.

Mr Zelenskyy has pleaded for a no-fly zone over his country and lashed out at Nato for refusing to impose one, warning that “all the people who die from this day forward will also die because of you”.

But as the United States and other Nato members send weapons for Kyiv, the conflict is already drawing in countries far beyond Ukraine’s borders.

As Russia cracks down on independent media reporting on the war, more major international news outlets said they were pausing their work there. Putin said nothing warrants imposing martial law at this point.

And in a warning of a hunger crisis yet to come, the UN World Food Programme has said millions of people inside Ukraine, a major global wheat supplier, will need food aid “immediately”.

The UN Security Council scheduled an open meeting for Monday on the worsening humanitarian situation.

The United Nations estimates that 12 million people in Ukraine and four million fleeing to neighbouring countries in the coming months will need humanitarian aid.

Kyiv’s central train station remained crowded with people desperate to flee. “People just want to live,” one woman, Ksenia, said.