"Counter-offensive and defensive actions are taking place," he said.

But he added that he would not talk in detail about which stage or state the counter-offensive was in.

The comments come after an escalation of fighting in the south and east of Ukraine and speculation about progress of the widely anticipated push.

Ukrainian troops are reported to have advanced in the east near Bakhmut and in the south near Zaporizhzhia, and have carried out long-range strikes on Russian targets.

But assessing the reality on the front lines is difficult, with the two warring sides presenting contrasting narratives: Ukraine claiming progress and Russia that it is fighting off attacks.

Russian President Vladimir Putin said in a video interview published Friday that Ukrainian forces had certainly begun their offensive but that attempted advances had failed with heavy casualties.

Speaking in Kyiv on Saturday, after talks with the Canadian PM Justin Trudeau, Mr Zelensky described the Russian leader's words as "interesting".

Shrugging his shoulders, raising his eyebrows and pretending not to know who Mr Putin was, Mr Zelensky said it was important that Russia felt "they do not have long left".

He also said that Ukraine's military commanders were in a positive mood, adding: "Tell that to Putin."

Analysing Ukraine's counter-offensive against Russia
Mr Trudeau announced 500 million Canadian dollars (£297m) in new military aid for Ukraine during the unannounced visit.

A joint statement issued after the talks said Canada supports Ukraine becoming a Nato member "as soon as conditions allow for it", adding that the issue would be discussed at the Nato Summit in Vilnius, Lithuania, in July.

Drone debris hits Odesa homes
The news conference followed an overnight Russian strike in which three people died and dozens were injured in the southern city of Odesa.

Falling debris from a shot-down Russian drone started a fire in a residential block in the Black Sea-port city, Ukrainian officials said.

The residential block in Odesa was damaged during a massive Russian drone strike

A separate overnight Russian attack targeted an airfield in the central region of Poltava.

Ukraine's air force said the Odesa attack, which lasted six hours, involved eight land-based missiles and 35 drones, and that air defence units were able to shoot down 20 drones and two cruise missiles.

"As a result of the air fight, debris from one of the drones fell onto a high-rise apartment, causing a fire," Natalia Humeniuk, the southern military command's spokesperson, said.

Emergency services said 27 people, including three children, were wounded, and that the fire had been quickly put out. Twelve people were rescued from the building, they said.

Images showed an apartment building in Odesa heavily damaged, with debris covering rooms and windows blown out. Others showed a large crater on the ground.

An airfield in the central region of Poltava was also hit by a Russian attack early on Saturday, with the local governor saying it involved ballistic and cruise missiles as well as drones. He said it caused damage to airfield infrastructure and equipment.

A 29-year-old was killed in a separate attack in the northeast Kharkiv region, officials said.

Meanwhile, fighting has escalated in recent days in the key southern Zaporizhzhia region, Russian officials say, with Ukraine forces reported to be trying to regain access to the Sea of Azov, which would split Russian forces.

Ukraine's hope of advances in the region, however, could be hindered by huge flooding in the south of the country after the Nova Khakovka dam was destroyed last week.

Breaching the Kakhovka dam – who benefits?
The flooding has covered around 230 square miles (596 sq km) either side of the Dnipro River.

Nato and Ukraine's military have accused Russia of blowing up the dam, while Russia has blamed Ukraine.