KYIV, Ukraine (AFP)— Ukraine on Sunday vowed to fight to the end in Mariupol after a Russian ultimatum expired for remaining forces to surrender in the southeastern port city where Moscow is pushing for a major strategic victory.

“The city still has not fallen,” Prime Minister Denys Shmyhal said hours after Moscow’s deadline for fighters holed up and surrounded in a sprawling fortress-like steelworks to surrender passed.

“There’s still our military forces, our soldiers. So they will fight to the end,” he told ABC’s “This Week”, with Moscow shifting its military focus to gaining control of the eastern Donbas region and forging a land corridor to already-annexed Crimea.

Russia’s defence ministry said that there were up to 400 mercenaries inside the encircled Azovstal steel plant, calling on Ukrainian forces inside to “lay down their arms and surrender in order to save their lives.”

Moscow claims Kyiv has ordered fighters of the nationalist Azov battalion to “shoot on the spot” anyone wanting to surrender.

– ‘Dead end’ –

Ukraine President Volodymyr Zelensky said that if Russian forces kill Kyiv’s troops remaining to defend the city, then a fledgling negotiation process to end nearly two months of fighting would be ended.

Russian President Vladimir Putin had already said the talks were at a “dead end.”

Shmyhal said that Ukraine wanted a diplomatic solution “if possible,” but added: “If the Russians wouldn’t like negotiations, we’ll fight to the end, absolutely. We will not surrender.

While several cities are under siege, he said, not one — with the exception of Kherson in the south — had fallen. He said more than 900 towns and cities had been liberated.

As Russia scales up attacks on Ukraine’s eastern flank, at least five people were killed and 13 wounded in a series of strikes in second city Kharkiv, just 21 kilometres (13 miles) from the Russian border and an air strike hit an armaments factory in Kyiv.

Maksym Khaustov, the head of the Kharkiv region’s health department, confirmed the deaths following a series of strikes that AFP journalists on the scene said had ignited fires throughout the city and torn roofs from buildings.

At one site, AFP saw a blood-stained coat next to a pool of fresh blood on the ground. A local reported hearing between six and eight missiles hit in the kind of strike that has become a daily occurrence.

On Friday, shelling of residential areas of the city killed 10 people. On Saturday, a strike claimed two more lives.