Ukrainian President Volodymyr Zelensky on Tuesday visited the heavily shelled frontline town of Avdiivka in the country's east, his official website said.

Zelensky visited "advanced positions" in the town close to the Russian-occupied city of Donetsk, and wished troops a happy Orthodox Easter, the website said. 

Zelensky was pictured sitting with soldiers at a table laid with traditional Easter cakes. Orthodox Easter was celebrated on Sunday.

The visit was announced hours after the Kremlin said Russian President Vladimir Putin had on Monday visited two frontline regions.

The Kremlin said on Tuesday that Putin had visited two frontline regions in Ukraine, prompting Kyiv to brand it a tour of the scenes of Russian "crimes".

Moscow portrayed the trip as a marker of its control in occupied Ukraine, but Russia does not fully hold those areas despite claiming them after a widely-condemned annexation. 

Putin's visit to Kherson and Lugansk, which was only made public a day after it happened, came as China's Defence Minister Li Shangfu was in Moscow to demonstrate what he called Beijing's "determination" to stronger Russia ties.

Russian President Vladimir Putin visiting the headquarters of the Dniepr military grouping in the Kherson region of Ukraine.

Moscow has been seeking allies to confront the West as its war in Ukraine causes immense destruction and suffering but has not neared Putin's goal of capturing control of the country.

"The president is now visiting the new regions more and more often," Kremlin spokesman Dmitry Peskov said, adding it was "absolutely important" that Putin as supreme commander-in-chief of Russia's armed forces "gets information on the spot".

The Kremlin chief's February 2022 invasion triggered the largest conflict in Europe since World War II, with Ukrainian forces now expected to be preparing a spring counter-offensive.

Mykhailo Podolyak, an advisor to President Volodymyr Zelensky, called Putin's trip "a 'special tour' of the mass murders' author", adding he went to Ukraine's occupied territories "to enjoy the crimes of his minions for the last time."

After Putin's visit was made public on Tuesday, Ukrainian officials said Russian forces had shelled the centre of the city of Kherson, killing one person and injuring nine.

Last week a Russian strike on a block of flats in the eastern Ukrainian city of Sloviansk killed 15, including a two-year-old boy, and wounded 24.

Russia was beaten back in northern and southern regions last year and Moscow's forces have made only incremental gains in eastern Ukraine.

Much of the fighting is now concentrated around the eastern town of Bakhmut which has become the longest and bloodiest battle of the conflict.

During his trip to Ukraine, Putin met Russian military commanders and discussed the situation on several fronts of the pro-Western country, the Kremlin said.

According to video footage released by the Kremlin, neither Defence Minister Sergei Shoigu nor Russia's top commander in Ukraine, Valery Gerasimov, accompanied Putin.

Putin's spokesman Peskov said it was not "rational" for all the top military commanders to "gather in one place" and both Shoigu and Gerasimov participated in the meetings remotely.

The footage showed Putin disembarking from a helicopter as he visited the headquarters of the Dnieper army group in the Kherson region and heard a report from Mikhail Teplinsky, commander of Russia's airborne troops.

He also visited national guard headquarters in Lugansk in eastern Ukraine and heard a report from Colonel-General Alexander Lapin.

"It's important for me to hear your opinion on the situation, to listen to you and to exchange information," Putin said in the video.

The Kremlin said in March that Putin had made a surprise trip to the port city of Mariupol, which Moscow captured after a long siege last spring.

In Moscow, Li told Shoigu his trip was aimed at demonstrating Beijing's "determination" to strengthen strategic ties with Russia.

Shoigu said it was "important that our countries see eye to eye on the issue of the ongoing transformation of the global geopolitical landscape".

- 'Creeping advances' - 

British military intelligence said on Tuesday that "heavy fighting" continued along the Donbas front line in eastern Ukraine.

"However, there is a realistic possibility that Russia has reduced troop numbers and is decreasing offensive action around Donetsk city, most likely to divert resources towards the Bakhmut sector," it said in a statement.

The statement said that in Bakhmut, Russia's regular troops and forces from the Wagner mercenary outfit continued to make "creeping advances."

Ukraine, the statement said, wants "to free-up an offensive force while Russia likely aspires to regenerate an operational reserve."

The commander of Ukrainian ground forces, Oleksandr Syrskyi, said Russian troops were not abandoning their goal of taking control of Bakhmut "at any cost," ramping up the use of heavy artillery and air strikes.

Kyrylo Budanov, chief of Ukraine's military intelligence, for his part said that Russia currently had "no offensive potential for a strategic offensive operation."

The head of the Ukrainian president's office, Andriy Yermak, meanwhile said he spoke with US national security adviser Jake Sullivan.