By JON GAMBRELL and CARA ANNA
LVIV, Ukraine (AP) -- Heavy fighting raged Thursday at the shattered steel plant in Mariupol as Russian forces sought to finish off the city's last-ditch defenders and complete the capture of the strategically vital Ukrainian port.
The bloody battle came amid growing speculation that President Vladimir Putin wants to present the Russian people with a major battlefield success -- or announce an escalation of the war -- in time for Victory Day on Monday. That is the biggest patriotic holiday on the Russian calendar, marking the Soviet Union's triumph over Nazi Germany.
Some 2,000 Ukrainian fighters, by Russia's most recent estimate, were holed up in the tunnels and bunkers under the sprawling Azovstal steelworks in Mariupol, the last pocket of resistance in a city largely reduced to rubble over the past two months. A few hundred civilians were also believed trapped there.
The Russians managed to get inside with the help of an electrician who knew the layout, said Anton Gerashchenko, an adviser to Ukraine's Internal Affairs Ministry.
"He showed them the underground tunnels which are leading to the factory," Gerashchenko said in a video posted late Wednesday. "Yesterday, the Russians started storming these tunnels, using the information they received from the betrayer."
The Kremlin denied its troops were storming the plant. The Kremlin has demanded the fighters surrender. They have refused. Russia has also accused them of preventing the civilians from leaving.
Meanwhile, 10 weeks into the devastating war, Ukraine's military claimed it recaptured some areas in the south and repelled other attacks in the east, further frustrating Putin's ambitions after his abortive attempt to seize Kyiv. Ukrainian and Russian forces are fighting village by village.
The head of Britain's armed forces, Chief of the Defense Staff Adm. Tony Radakin, said Putin is "trying to rush to a tactical victory" before Victory Day. But he said Russian forces are struggling to gain momentum in the Donbas.
Radakin told British broadcaster Talk TV that Russia is using missiles and weapons at such a rate that it is in a "logistics war" to keep supplied. He added: "This is going to be a hard slog."
Fearful of new attacks surrounding Victory Day, the mayor of the western Ukrainian city of Ivano-Frankivsk urged residents to leave for the countryside over the long weekend and warned them not to gather in public places.
And the southeastern city of Zaporizhzhia, a key transit point for evacuees from Mariupol, announced a curfew from Sunday evening through Tuesday morning.
In other developments, Belarus' authoritarian president, Alexander Lukashenko, defended Russia's invasion of Ukraine in an interview with The Associated Press but said he didn't expect the conflict to "drag on this way."
As the battle raged in Mariupol, Russian Defense Ministry spokesman Maj. Gen. Igor Konashenkov said Russian bombardment Thursday hit dozens of Ukrainian military targets, including troop concentrations in the east, an artillery battery near the eastern settlement of Zarozhne, and multiple rocket launchers near the southern city of Mykolaiv.
Five people were killed and at least 25 wounded in shelling of cities in the Donbas over the past 24 hours, Ukrainian officials said. The attacks damaged houses and a school.
Ukrainian forces said they made some gains on the border of the southern regions of Kherson and Mykolaiv and repelled 11 Russian attacks in the Donetsk and Luhansk regions that make up the Donbas.
With the challenge of mine-clearing and rebuilding after the war in mind, Ukrainian President Volodymyr Zelenskyy announced the launch of a global fundraising platform called United24.
In addition, a Ukrainian cabinet body began to develop proposals for a comprehensive postwar reconstruction plan, while Zelenskyy also urged Western allies to put forward a program similar to the post-World War II Marshall Plan plan to help Ukraine rebuild.