KYIV, Ukraine (AP) — Moscow officials claimed that Ukrainian forces were making a major effort to punch through Russian defensive lines in southeast Ukraine for a second day Monday. Kyiv authorities didn't confirm the attacks and suggested the claim was a Russian misinformation ruse.

Vladimir Rogov, a Moscow-installed official in southeast Ukraine’s partly-occupied Zaporizhzhia province, said fighting resumed there early Monday after Russian defenses beat back a Ukrainian advance the previous day.

Rogov claimed that “the enemy threw an even bigger force into the attack than yesterday.” The new attempt to break through the front line was “more large-scale and organized,” he said, adding: “A battle is underway.”

Rogov's comments came after Moscow also claimed to have thwarted large Ukrainian attacks in the eastern Donetsk region, another of the four regions that President Vladimir Putin claimed as Russian territory last fall and partially controls.

Russia's Defense Ministry claimed it had pushed back a “large-scale” assault Sunday at five points in Donetsk province.

The claims could not be independently verified, and Ukrainian officials did not confirm any assaults, but the reports fueled speculation that a major Ukrainian ground operation could be underway as part of an anticipated counteroffensive.

A video published by the Ukrainian Defense Ministry showed soldiers putting a finger to their lips in a sign to keep quiet. “Plans love silence,” it said on the screen. “There will be no announcement of the start.”

The Center for Strategic Communications of the Armed Forces of Ukraine said on Telegram that Russian forces were “stepping up their information and psychological operations.”

“In order to demoralize Ukrainians and mislead the community (including their own population), Russian propagandists will spread false information about the counteroffensive, its directions and the losses of the Ukrainian army. Even if there is no counteroffensive,” a statement on Telegram read.

Ukrainian officials have kept Russia guessing about when and where it might launch a counteroffensive, or even whether it had already started. A possible counteroffensive, using advanced weapons supplied by Western allies, could provide a major morale boost for Ukrainians 15 months after Russia's full-scale invasion.

Recent military activity, including drone attacks on Moscow, cross-border raids into Russia and sabotage and drone attacks on infrastructure behind Russian lines, has unnerved Russians. Analysts say those actions may represent the start of the counteroffensive.

Driving out the Kremlin's forces is a daunting challenge. Russia has built extensive defensive lines, including trenches, minefields and anti-tank defenses. The front line stretches for 1,100 kilometers (684 miles).

Ukraine could launch simultaneous pushes in different areas, analysts say.

Michael Clark, the former head of the Royal United Services Institute think tank, said the “increased tempo” of activity in recent weeks likely marked the start of the counteroffensive and that June is likely to see the start of Ukraine’s ground operation.

“There’s something going on,” he told the BBC.

Russian Defense Ministry spokesman Igor Konashenkov claimed that 250 Ukrainian personnel were killed in the fighting in Donetsk province, and 16 Ukrainian tanks, three infantry fighting vehicles and 21 armored combat vehicles were destroyed.

“The enemy’s goal was to break through our defenses in the most vulnerable, in its opinion, sector of the front,” Konashenkov said. “The enemy did not achieve its tasks. It had no success.”

The Russian Defense Ministry said the alleged Donetsk attack started Sunday morning. It was unclear why it waited until early Monday to announce it.

Ukraine often waits until the completion of its military operations to confirm its actions, imposing news blackouts in the interim.

For months, Ukrainian officials have spoken of plans to launch a counteroffensive to reclaim territory Russia has occupied since invading the country on Feb. 24, 2022, as well as the Crimean Peninsula, which it seized in 2014.

At least two factors have been at play in the timing: better ground conditions for the movement of troops and equipment after the winter, and the deployment of more advanced Western weapons and training of Ukrainian troops to use them.

The Russian Defense Ministry spokesman said Ukraine used six mechanized and two tank battalions in the Donetsk attacks. The ministry released a video claiming to show destruction of some of the equipment in a field.

In a rare specific mention of the presence of Russia’s top military leaders in battlefield operations, Konashenkov said the chief of the general staff of the Russian armed forces, Gen. Valery Gerasimov, “was at one of the forward command posts.”

Announcing Gerasimov’s direct involvement could be a response to criticism by some Russian military bloggers and by Yevgeny Prigozhin, the head of Russian mercenary group Wagner, that Russia’s military brass hasn’t been visible enough at the front or taken sufficient control or responsibility for their country’s military operations in Ukraine.