Russian President Vladimir Putin met his commanders in two regions of Ukraine that Moscow claims to have annexed, while Russian forces stepped up heavy artillery bombardments and air strikes on Tuesday on the devastated Ukrainian city of Bakhmut.

Ukraine’s President Volodymyr Zelensky, meanwhile, visited troops in the eastern town of Avdiivka, about 70 km southwest of Bakhmut, and was briefed on the battlefield situation, his office said.

On his visit to Avdiivka on Tuesday, Zelensky’s office said he had handed out awards to his troops, telling them: “I have the honour to be here today, to thank you for your service, for defending our land, Ukraine, our families.”

The Kremlin said Putin on Monday had attended a military command meeting in Ukraine’s southern Kherson region and visited a national guard headquarters in eastern Luhansk.

Putin heard reports from commanders of the airborne forces and the Dnieper army group as well as other senior officers who briefed him on the situation in the Kherson and Zaporizhzhia regions in the south. Neither defence minister Sergei Shoigu nor chief of the general staff Valery Gerasimov joined Putin on his trip as a security precaution, the Kremlin said.

A senior Ukrainian presidential aide, Mykhailo Podolyak, took to Twitter to mock Putin’s trip as a “’special tour’ of the mass murders’ author in the occupied and ruined territories to enjoy the crimes of his minions for the last time”.

Kyiv and the West accuse Russian forces of committing war crimes in occupied Ukrainian territory, which Moscow denies.

Kherson, Zaporizhzhia, Luhansk and Donetsk are the four regions that Putin proclaimed annexed last September following what Ukraine said were sham referendums. Russian forces only partly control the four regions.

Russian troops retreated from Kherson city, the regional capital, last November, and have been reinforcing their positions on the opposite bank of the Dnipro River in anticipation of a Ukrainian counteroffensive this spring.

While numerous western leaders have made their way to Kyiv for talks with President Zelensky since Russian forces invaded 14 months ago, Putin has rarely visited parts of Ukraine under Russian control. Last month, he visited Crimea — annexed by Russia in 2014 — and the southeastern city of Mariupol in Donetsk region.

A Russian winter offensive failed to make much progress and its troops have been bogged down in a series of battles in the east and south, where advances have been incremental and come at a huge cost to both sides.

Fighting has raged in and around Bakhmut in Donetsk region for months.

“Currently, the enemy is increasing the activity of heavy artillery and the number of air strikes, turning the city into ruins,” the commander of Ukraine’s ground forces, General Oleksandr Syrskyi, said on Tuesday.