Russian and Ukrainian forces have exchanged missile and artillery barrages that killed at least seven people as both sides refused to concede any ground – despite recent military setbacks for Moscow and the toll on the invaded country after almost seven months of war.

Russian missile strikes in the southern city of Zaporizhzhia left one person dead and five others wounded, Ukrainian officials said.

Officials in the separatist-controlled city of Donetsk said Ukrainian shelling killed at least six people.

Demonstrating that neither side was ready to ease the fighting, the exchange of fire came hours after the two sides made a major prisoner swap and the day after Russian President Vladimir Putin called up reserve troops to supplement his forces.

Kyrylo Tymoshenko, the deputy of the Ukrainian president’s office, said a hotel in Zaporizhzhia was struck and rescuers were trying to free people trapped in the rubble.

The governor of the Zaporizhzhia region, Oleksandr Starukh, said Russian forces had targeted infrastructure facilities and also damaged nearby apartment buildings.

The region is one of four where officials installed by Moscow plan to hold referendums starting on Friday on becoming part of Russia, but the city itself is in Ukrainian hands.

Meanwhile, the mayor of the separatist-controlled city of Donetsk, Alexei Kulemzin, said at least five people where killed when Ukrainian shelling on Thursday hit a covered market and a minibus.

Overnight, one person was killed during Russian shelling in Nikopol, across the river from the Zaporizhzhia nuclear power station, according to the Dnipropetrovsk regional governor.

Just hours before Thursday’s attacks, the high-profile prisoner swap saw 215 Ukrainian and foreign fighters exchanged — 200 of them for a single person, an ally of Mr Putin’s.

Kremlin spokesman Dmitry Peskov would not confirm if the lone Mr Putin ally — pro-Russian Ukrainian opposition leader Viktor Medvedchuk — was part of the swap.

Among the freed fighters were Ukrainian defenders of a steel plant in Mariupol during a long Russian siege and 10 foreigners, including five British citizens and two US military veterans who had fought with Ukrainian forces.

A video on the BBC news website showed two of the released British men, Aiden Aslin and Shaun Pinner, speaking on a plane.

It said they had arrived in Riyadh, Saudi Arabia.

“We just want to let everyone know that we’re now out of the danger zone and we’re on our way home to our families,” Mr Aslin said in the video, as Mr Pinner added: “By the skin of our teeth.”

The speed with which the Russian missile attack came after the swap suggested that the Kremlin was seeking to dispel any notion of weakness or waning determination to achieve its wartime aims following recent battlefield losses and setbacks that gravely undercut the aura of Russian military might.

Those losses culminated on Wednesday in Mr Putin’s order for a partial mobilisation of reservists to bolster his forces in Ukraine.

The order sparked rare protests in dozens of Russian cities and was derided in the West as an act of weakness and desperation.

Nearly 1,200 Russians were arrested in the anti-war demonstrations, according to the independent Russian human rights group OVD-Info.

Mr Putin’s partial call-up was short on details, raising concerns of a wider draft that sent some Russians scrambling to buy plane tickets to flee the country.

One Russian man who arrived in the Armenian capital’s airport with his 17-year-old son said he had made plans for such a scenario.

Mr Peskov, the Kremlin spokesman, said the mobilisation was needed because Russia was “de facto facing all of Nato”, a reference to the military aid and other support that alliance members given Ukraine.

Speaking in New York on Thursday, German foreign minister Annalena Baerbock praised Russian anti-war protesters and said no one inside the country can continue turning a blind eye to what’s happening in Ukraine because “every Russian is now going to be at risk of being drafted into this war”.

A senior Kremlin official on Thursday repeated Mr Putin’s threat to use nuclear weapons if Russian territory comes under attack.

Dmitry Medvedev, deputy head of Russia’s Security Council, said strategic nuclear weapons are one of the options to safeguard Russian-controlled territories in eastern and southern Ukraine.

The remark appeared to serve as a warning that Moscow could also target Ukraine’s Western allies.

Pro-Moscow authorities in Ukraine’s Russian-occupied regions are preparing to hold referendums on becoming part of Russia — a move that could allow Moscow to escalate the war.

The votes start on Friday in the Luhansk, Kherson, Zaporizhzhia and Donetsk regions.

Foreign leaders have called the votes illegitimate and non-binding.

Ukrainian President Volodymyr Zelensky said they were a “sham” and “noise” to distract the public.

Germany, meanwhile, said it is ready to accept Russian military deserters.

Interior minister Nancy Faeser told the Frankfurter Allgemeine Sonntagszeitung that anyone who “courageously opposes Putin’s regime and therefore puts himself in the greatest danger” can apply for asylum in Germany.