Ukraine says it has been forced to alter its plans for a spring counteroffensive after a leak of what appeared to be classified US intelligence documents revealed top secret military details, according to a report.

The documents, which emerged online, included details ranging from the war in Ukraine, China, the Middle East and Africa - and have US officials scrambling to identify the leak's source, with some experts saying it could be an American.

Now, citing a source close to Ukrainian President Volodymyr Zelensky, CNN has reported that Ukraine has been forced to amend some of its military plans ahead of a much-vaunted counter-offensive because of the information revealed in the leaks.

Meanwhile, Russian forces are continuing to press attacks in Ukraine's eastern Donetsk region, focusing on two cities and pounding Ukrainian positions with air strikes and artillery barrages, Kyiv said on Monday.

The commander of Ukraine's ground forces said the Russians were destroying buildings in besieged Bakhmut in what he called 'scorched earth' tactics as elsewhere a missile strike killed a father and his 11-year-old daughter.

Ukraine says it has been forced to alter its plans for a spring counteroffensive after a leak of what appeared to be classified US intelligence documents, as the commander of Kyiv's ground forces said that Russia is resorting to using 'scorched earth' tactics in Bakhmut.