KHARKIV, Ukraine (AP) — Ukrainian forces fought village by village Saturday to hold back a Russian advance through the country’s east, while the United Nations (UN) worked to broker a civilian evacuation from the last defensive stronghold in the bombed-out ruins of the port city of Mariupol.

An estimated 100,000 civilians remain in the city, and up to 1,000 are living beneath a sprawling Soviet-era steel plant, according to Ukrainian officials. Ukraine has not said how many fighters are also in the plant, the only part of Mariupol not occupied by Russian forces, but Russia put the number at about 2,000.

Russian state media outlets reported Saturday that 25 civilians had been evacuated from the Azovstal steelworks, though there was no confirmation from the UN Russia’s RIA Novosti news agency said 19 adults and six children were brought out, but gave no further details.

A top official with the Azov Regiment, the Ukrainian unit defending the plant, said 20 civilians were evacuated during a cease-fire, though it was not clear if he was referring to the same group as the Russian news reports.

“These are women and children,” Sviatoslav Palamar said in a video posted on the regiment’s Telegram channel. He also called for the evacuation of the wounded: “We don’t know why they are not taken away and their evacuation to the territory controlled by Ukraine is not being discussed.”

Video and images from inside the plant, shared with The Associated Press by two Ukrainian women who said their husbands are among the fighters refusing to surrender there, showed unidentified men with stained bandages; others had open wounds or amputated limbs.

A skeleton medical staff was treating at least 600 wounded people, said the women, who identified their husbands as members of the Azov Regiment of Ukraine’s National Guard. Some of the wounds were rotting with gangrene, they said.

In the video the men said that they eat just once daily and share as little as 1.5 litres (50 ounces) of water a day among four people, and that supplies inside the besieged facility are depleted.

One shirtless man appeared to be in pain as he described his wounds: two broken ribs, a punctured lung and a dislocated arm that “was hanging on the flesh.”

“I want to tell everyone who sees this: If you will not stop this here, in Ukraine, it will go further, to Europe,” he said.

AP could not independently verify the date and location of the video, which the women said was taken in the last week in the maze of corridors and bunkers beneath the plant.

The women urged that Ukrainian fighters also be evacuated alongside civilians, warning they could be tortured and executed if captured. “The lives of soldiers matter too,” Yuliia Fedusiuk told AP in Rome.

In his nightly video address late Saturday, Ukrainian President Volodymyr Zelenskyy switched into Russian to urge Russian troops not to fight in Ukraine, saying even their generals expect that thousands more of them will die.

The president accused Moscow of recruiting new soldiers “with little motivation and little combat experience” so that units gutted early in the war can be thrown back into battle.

“Every Russian soldier can still save his own life,” Zelenskyy said. “It’s better for you to survive in Russia than to perish on our land.”

In other developments:

— Ukrainian Deputy Agriculture Minister Taras Vysotsky said in televised remarks that Russian forces have seized hundreds of thousands of tons of grain in territory under their control. Ukraine is a major grain producer, and the invasion has pushed up world prices and raised concerns about shortages.

— A Russian rocket attack destroyed the airport runway in Odesa, Ukraine’s third-most populous city and a key Black Sea port, the Ukrainian army said.

— The bodies of three men were found buried in a forest near the Kyiv suburb of Bucha, the head of Kyiv’s regional police force said. The men, whose bodies were found Friday, had been tortured before they were shot in the head, Andriy Nebytov wrote on Facebook. Ukrainian officials have alleged that retreating Russian troops carried out mass killings of civilians in Bucha.

— Russian Foreign Minister Sergey Lavrov said in an interview that Russian and Ukrainian negotiators talk “almost every day.” However, he told Chinese state news agency Xinhua, “progress has not been easy.”

— Two buses sent to evacuate residents from the eastern town of Popasna were fired upon, and contact with the organisers was lost, Mayor Nikolai Khanatov said: “We know that (the buses) reached the town and then came under fire from an enemy sabotage and reconnaissance group.”

Getting a full picture of the unfolding battle in eastern Ukraine has been difficult because airstrikes and artillery barrages have made it extremely dangerous for reporters to move around. Also, both Ukraine and Moscow-backed rebels have introduced tight restrictions on reporting from the combat zone.

But Western military analysts suggested that the offensive in the Donbas region, which includes Mariupol, was going much slower than planned. So far, Russian troops and the separatists appeared to have made only minor gains in the month since Moscow said it would focus its military strength in the east.

Numerically, Russia’s military manpower vastly exceeds Ukraine’s. In the days before the war began, Western intelligence estimated Russia had positioned near the border as many as 190,000 troops; Ukraine’s standing military totals about 200,000, spread throughout the country.

Yet, in part because of the tenacity of the Ukrainian resistance, the US believes the Russians are “at least several days behind where they wanted to be” as they try to encircle Ukrainian troops in the east, said a senior US defence official who spoke on condition of anonymity to discuss the American military’s assessment.

With plenty of firepower still in reserve, Russia’s offensive still could intensify and overrun the Ukrainians. Overall the Russian army has an estimated 900,000 active-duty personnel. Russia also has a much larger air force and navy.

Hundreds of millions of dollars in military assistance has flowed into Ukraine since the war began, but Russia’s vast armouries mean Ukraine’s needs are nearly inexhaustible.

Mariupol officials have described dire shortages of food, water and medicine. UN humanitarian spokesman Saviano Abreu said the world organisation was negotiating with authorities in Moscow and Kyiv, but he could not provide details of the ongoing evacuation effort “because of the complexity and fluidity of the operation.”

“There is, right now, ongoing, high-level engagements with all the governments, Russia and Ukraine, to make sure that you can save civilians and support the evacuation of civilians from the plant,” Abreu told AP. He would not confirm video posted on social media purportedly showing UN-marked vehicles in Mariupol.

Ukraine has blamed the failure of numerous previous evacuation attempts on continued Russian shelling.