Belarus has invaded Ukraine joining Russia to become the second country to attack them, the Ukrainian government has said.
A tweet from the official Twitter account of the Ukrainian parliament claimed that troops "have entered" the region of Chernihiv, in northern Ukraine.
This was backed up by the Latvian Defence Minister, Dr Artis Pabriks, who said Belarusian troops had crossed the border into Ukraine.
He told the Commons Foreign Affairs Committee: “This basically means we have two aggressives at this moment officially.
“I am very much concerned that Russian troops, following orders from the top, will go into the mode similar to that President Assad was using against his population."
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It comes only hours after Belarusian president and Putin supporter Aleksandr Lukashenko claimed he had no plans to join Putin's war.
He was quoted on Tuesday denying that Russian troops were attacking Ukraine from Belarusian territory.
The Tweet from the official @verkhovna_rada Twitter account for the parliament of Ukraine, said: "Belarusian troops have entered Chernihiv region.
"The information was confirmed to the public by Vitaliy Kyrylov, spokesman for the North Territorial Defence Forces.”
It means Lukashenko's troops have joined the conflict on the sixth day of the invasion as Russia continues to push ahead to try and take key Ukrainian cities.
According to local reports from the region, a column of 33 tanks rolled past residents of Slabyn, Pakul and Mykhailo-Kotsyubynsky at 11.30am local time.
These were northern border towns, close to Belarus, and not far from Kyiv.
On top of this, Lukashenko has since said that he is deploying more forces to his country's border with Ukraine.
State news agency agency Belta quoted him as saying: "Those are well trained rapid deployment groups which are ready to stop any provocation and any military action against Belarus."
Previously, a US official had predicted Belarus could send in troops to support Russia.
Speaking to The Washington Post on Sunday, the official said: “It’s very clear Minsk is now an extension of the Kremlin.”
However, the Ministry of Defence said this morning that continued logistical difficulties held Putin’s forces up.
They added that due to a failure on Moscow's behalf to seize control of Ukrainian airspace, they had shifted their impetus to nighttime operations to attempt to reduce losses.
The last 24 hours has seen Putin's forces make little progress but increase their artillery attacks north of Kyiv, and around Kharkiv and Chernihiv.
This comes as a 40 mile Russian armour convoy heads for the Ukrainian capital, in an effort to break the deadlock between the two sides.
Lithuanian Foreign Minister Gabrielius Landsbergis said it is clear that Putin has "no boundaries" to what instruments he will use against Ukraine.
Speaking to the Foreign Affairs Committee, he said: "It is possible that this war will become a massacre."
Speaking today, Prime Minister Boris Johnson said evidence of Vladimir Putin's attacks on civilians could be used in any future trail at The Hague.
Speaking in Warsaw, Mr Johnson said: "There's no doubt that he is already using barbaric tactics, bombing civilian areas.
"I have seen the reports about cluster bombs and thermobaric weapons, they will, of course, have to be verified.
"I think that everybody involved in the Russian onslaught should understand that all this will be collated in evidence to be used at a future time in what could be proceedings before the International Criminal Court."
This came after overnight reports accused Putin of using vacuum and cluster bombs on Ukraine.
These can cause massive damage and horrific injuries and are banned by the Geneva Convention. The reports followed warnings that Putin may escalate the conflict if his army continued to struggle.
The General Staff of the Armed Forces of Ukraine today claimed it had inflicted 5,710 Russians casualties across the first five days of fighting.
And Ukrainian officals confirmed the first deaths after this morning's rocket attacks on Kharkiv.
At least 10 people were killed and 35 were wounded, Interior Ministry adviser Anton Herashchenko said.
He added: "The rubble is being cleared and there will be even more victims and wounded."
Following on from the brutal attack, Ukrainian President Volodymyr Zelensky accused Russia of 'state terrorism'.
Mr Zelensky said: "The terror aims to break us, to break our resistance."
Kyiv’s envoy to Britain, Vadym Prystaiko, gave a bleak assessment of the six-day-old war launched by the Russian president as Ukraine continues to fight.
He warned Ukrainians were struggling to access cash as Kremlin forces encircled major cities.
Asked about the potential for a “food crisis” and looting, the diplomat told the Commons Foreign Affairs Select Committee: “They will try to crush the will of the Ukrainian people to resist.
“We see problems with cash for example - people just running out of cash and they have interruption in their services.
“The terminals won’t be working and we will have to come up with some military solution to the distribution of food.”
