Exiled Belarusian opposition leader Svetlana Tikhanovskaya on Tuesday said she believed it was "almost impossible" for her country's troops to join Russia's war in Ukraine, adding that army morale is low. 

Long-term Kremlin ally Belarus, led by strongman Alexander Lukashenko, has supported Russia since President Vladimir Putin's invasion of Ukraine on February 24 by acting as a rear base for Moscow's forces. 

"I really doubt that Belarussian troops... will participate in the invasion of Ukraine," Tikhanovskaya told reporters on a visit to Warsaw. 

"Of course I can't guarantee this but according to the intelligence, according to expert opinions, it's almost impossible," she added. 

"The Belarussian army is extremely demoralised. They don't want to fight with Ukrainians... They don't want to die for Lukashenko or for Putin."

Tikhanovskaya spoke after Lukashenko said Saturday his army had shot down missiles fired into their territory from Ukraine.

While he denied his country was seeking to intervene in the conflict between Russia and Ukraine, he issued a warning aimed at Kyiv and its Western allies.

"We will only fight in one case. If you... enter our land, if you kill our people, then we will respond," he said, warning that Belarus would reply "instantly" to an enemy strike on its soil.

Two years ago, Belarus faced historic protests against the re-election of Lukashenko, who has ruled the ex-Soviet country with an iron fist for more than two decades. 

Thousands of activists were arrested in the crackdown and the key leaders of the opposition movement are now either jailed or in exile.  

Among them is Tikhanovskaya, a political novice who ran against Lukashenko in the August 2020 polls in place of her jailed husband. 

She now leads the Belarusian opposition from exile in Lithuania, while her husband Sergei Tikhanovsky is serving 18 years in prison on what supporters say are politically motivated charges.