LVIV, Ukraine (AP) — What looked like a breakthrough cease-fire to evacuate residents from two cities in Ukraine quickly fell apart Saturday as Ukrainian officials said the work to remove civilians had halted amid shelling hours after Russia announced the deal.

The Russian defence ministry earlier said it had agreed on evacuation routes with Ukrainian forces for Mariupol, a strategic port in the southeast, and the eastern city of Volnovakha. The vaguely worded statement did not make clear how long the routes would remain open.

“The Russian side is not holding to the cease-fire and has continued firing on Mariupol itself and on its surrounding area,” said Kyrylo Tymoshenko, the deputy head of President Volodymyr Zelenskyy’s office. “Talks with the Russian Federation are ongoing regarding setting up a cease-fire and ensuring a safe humanitarian corridor.”

Russia breached the deal in Volnovakha as well, Deputy Prime Minister Iryna Vereshchuk told reporters. “We appeal to the Russian side to stop firing,” she said. Meanwhile, Russian outlet RIA Novosti carried a Russian defence ministry claim that the firing came from inside both communities against Russian positions.

The struggle to enforce the cease-fire showed the fragility of efforts to stop fighting across Ukraine as people continued to flee the country by the thousands.

“We are doing everything on our part to make the agreement work,” Zelenskyy said. “This is one of the main tasks for today. Let’s see if we can go further in the negotiation process.”

Mariupol had become the scene of growing misery amid days of shelling that knocked out power and most phone service and raised the prospect of food and water shortages for hundreds of thousands of people in freezing weather. Pharmacies are out of medicine, Doctors Without Borders said.

A top official in Mariupol had said the evacuations were to start at 11:00 am (9:00 am GMT) and the cease-fire was to last until 4:00 pm (2:00 pm GMT). Pavlo Kirilenko, head of the Donetsk military-civil administration that includes the city, said the humanitarian corridor would extend to Zaporizhzhia, 226 kilometres (140 miles) away.

The head of Ukraine’s security council, Oleksiy Danilov, had urged Russia to create humanitarian corridors to allow children, women and the older adults to flee the fighting, calling them “question No 1.”

Diplomatic efforts continued as US Secretary of State Antony Blinken arrived in Poland to meet with 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. Blinken would visit a border post to meet refugees later in the day.

As Russian forces batter strategic locations elsewhere, Ukrainian President Volodymyr Zelenskyy has lashed out at NATO for refusing to impose a no-fly zone over his country, warning that “all the people who die from this day forward will also die because of you”.

NATO said a no-fly zone could provoke widespread war in Europe with nuclear-armed Russia. But as the United States and other NATO members send weapons for Kyiv and more than one million refugees spill through the continent, the conflict is already drawing in countries far beyond Ukraine’s borders.

Russia continues to crack down on independent media reporting on the war, also blocking Facebook and Twitter, and more outlets say they are pausing their work inside the country.

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

Ukraine’s president was set to brief US senators Saturday by video conference as Congress considers a request for US$10 billion in emergency funding for humanitarian aid and security needs.

In a bitter and emotional speech late Friday, Zelenskyy criticised NATO over the lack of a no-fly zone, warning that “the history of Europe will remember this forever”.

A no-fly zone would bar all unauthorised aircraft from flying over Ukraine.

NATO Secretary General Jens Stoltenberg had ruled out that possibility. “The only way to implement a no-fly zone is to send NATO fighter planes into Ukrainian airspace, and then impose that no-fly zone by shooting down Russian planes,” he said.

In a separate video message to antiwar protesters in several European cities, Zelenskyy appealed for help. “If we fall, you will fall,” he said.

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.

Russia’s attack on Friday on Ukraine’s largest nuclear power plant, in Zaporizhzhia, caused global alarm, but Russian forces did not make significant progress in their offensive to sever Ukraine’s access to the Black Sea and the Sea of Azov, which would deal a severe blow to the country’s economy.

A vast Russian armoured column threatening Ukraine’s capital remained stalled outside Kyiv, but Russia’s military has launched hundreds of missiles and artillery attacks on cities and other sites across the country.

As homes in the northern city of Chernihiv burned from what locals described as Russian shelling, one resident accused Europe of merely looking on. “We wanted to join NATO and the EU and this is the price we are paying, and NATO cannot protect us,” she said.

At least 331 civilians have been confirmed killed since the fighting began but the true number is probably much higher, the UN human rights office said.

Kyiv’s central train station remained crowded with people desperate to join the more than 1.4 million who have fled Ukraine. “People just want to live,” one woman, Ksenia, said.