A tweet from the Ukrainian parliament on Tuesday morning followed earlier local media reports that Belarusian troops had arrived in the north of the country as the conflict entered its sixth day.
The official Verkhovna Rada of Ukraine Twitter account posted: “Belarusian troops entered Chernihiv region.
“The information was confirmed to the Public by Vitaliy Kyrylov, spokesman for the North Territorial Defense Forces. More details later.”
According to local media reports, a Belarusian column of 33 units entered Chernihiv, with mobile communications cut.
Belarus - a servant of Moscow under strongman leader Alexander Lukashenko - has already been used as launch pad by Russian troops, who gathered there on the pretext of joint military exercises before last Thursday’s full-scale invasion of Ukraine.
Shortly after the Ukrainian parliament tweeted, Mr Lukashenko said his country was deploying more forces to its border with Ukraine to “stop any provocation against Belarus”.
“Those are well trained rapid deployment groups which are ready to stop any provocation and any military action against Belarus,” state news agency Belta quoted the president as saying.
Just hours earlier, Mr Lukashenko said his country had no plans to join Russia’s military operation in Ukraine, and denied allegations by Kyiv that Russian troops were attacking from Belarus’ territory, Belta reported.
Satellite images taken on Monday by US imaging firm Maxar Technologies showed a significant Russian military convoy north of Kyiv, and additional ground forces deployments and ground attack helicopter units in southern Belarus, less than 20 miles north of the Ukraine border.
A referendum in Belarus on Sunday approved a new constitution ditching its non-nuclear status, paving the way for a possible deployment of Russian nuclear weapons on Belarusian soil for the first time since the country gave them up after the fall of the Soviet Union.
Speaking at a polling station on Sunday, Mr Lukashenko said he could ask Russia to return nuclear weapons to Belarus.
"If you (the West) transfer nuclear weapons to Poland or Lithuania, to our borders, then I will turn to Putin to return the nuclear weapons that I gave away without any conditions," the Belarusian president said.
Ukrainian president Volodymyr Zelensky said on Sunday that had spoken with Mr Lukashenko, and later appealed to Belarus to stay out of the conflict.
“We are your neighbors. We, Ukrainians. Be Belarus, not Russia! You are making this choice right now,” Mr Zelensky said in a recorded message.
The European Union’s foreign affairs chief, Josep Borrell, last week said Mr Lukashenko was allowing his nation to become a Russian satellite state, while a US official on Sunday said that “Minsk is now an extension of the Kremlin”.
Belarus’ leader turned to Russia for support and loans after 2020 protests against a disputed election that opponents say Mr Lukashenko rigged to sustain his 28-year-long rule.
In a separate development on Tuesday, Mr Lukashenko also said that the start of talks between Ukraine and Russia - which were held in Belarus on Monday - raises hope that hostilities may end, according to the RIA news agency.
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