KYIV: Russian forces pressed attacks on frontline cities in eastern Ukraine on Monday, while Ukrainian officials played down a report that Kyiv had had to amend some military plans ahead of a counteroffensive due to a leak of classified US documents.

The Russians were pounding Ukrainian positions around besieged Bakhmut in the eastern Donetsk region and other cities and towns with air strikes and artillery barrages, Kyiv said.

The commander of Ukraine’s ground forces said the Russians were destroying buildings and positions in Bakhmut in what he called “scorched earth” tactics.

Russia’s assault on Bakhmut, a small city on the edge of a chunk of Russian-controlled territory in Donetsk, has for months been the focus of the biggest battle of the war, now in its second year.

The Ukrainian military said on Sunday fighting was heaviest along the western approaches to Bakhmut — a regional transport and logistics hub prior to the war. Russian forces were also targeting the city of Avdiivka, it said.

As the battles ground on, US media outlet CNN reported that Ukraine had been forced to amend some of its military plans ahead of an anticipated counter-offensive due to a leak of classified US documents. It cited a source close to Ukrainian President Volodymyr Zelenskiy.

US officials are trying to find the source of the leak of dozens of secret documents detailing an array of topics, including information on the Ukraine conflict, in which the United States has supplied Kyiv with huge amounts of weapons and other support and led international condemnation of Moscow’s invasion.

Asked about the CNN report, Ukrainian presidential aide Mykhailo Podolyak said Kyiv’s strategic plans remained unchanged but that specific tactical plans were always subject to change.

The secretary of the National Security and Defence Council, Oleksiy Danilov, said: “We are working on our own plans... The opinion of people who have nothing to do with this do not interest us... The circle of people who possess information is extremely restricted.” Ukrainian officials said on Friday, the documents contained fictitious information and looked like a Russian disinformation campaign.

Some national security experts and US officials say they suspect the leaker could be American, given the breadth of topics covered by the documents, but they do not rule out pro-Russian actors.

A Ukrainian counteroffensive has long been expected after months of attritional warfare in the east. A Russian winter offensive failed to make much progress and its troops have got bogged down in a series of battles where any advances are incremental and come at a huge cost. The Ukrainian defenders have also taken heavy casualties.

On Monday, Ukrainian ground forces commander Colonel General Oleksandr Syrskyi said the defence of Bakhmut continued. “The situation is difficult but controllable,” he said, quoted by Ukraine’s Media Military Centre.