Defence Secretary Ben Wallace has announced the "most significant package of combat power to date to accelerate Ukrainian success".
Making a statement in the Commons, he told MPs: "In December, I told the House that I was developing options to respond to Russia's continued aggression in a calibrated and determined manner.
"Today, I can announce the most significant package of combat power to date to accelerate Ukrainian success.
"This includes a squadron of Challenger 2 tanks with armoured recovery and repair vehicles. We will donate AS90 guns to Ukraine. This batch comprises a battery of eight guns of high readiness and two further batteries at varying stages of readiness.
"This donation will not impact our existing AS90 commitment in Estonia."
The commitment by Mr Wallace follows an earlier announcement by Prime Minister Rishi Sunak who agreed to deliver a squadron of tanks to Ukraine to aid the country's efforts in re-taking territory lost to Russian forces.
The Prime Minister hopes the UK's intensifying support will increase the pressure on Russian President Vladimir Putin and galvanise support among Western allies.
He signed off on sending 14 British Army Challenger 2 main battle tanks to Kyiv, as well as around 30 AS90 self-propelled guns during a call with Ukrainian leader Volodymyr Zelensky over the weekend.
Mr Wallace told the House of Commons: "Over the last four weeks, extremely heavy and attritional fighting has continued, especially around the Donetsk Oblast town of Bakhmut, and in the less reported-on sector of Kremina, in Luhansk. Over Christmas, Russia has continued its assault on Ukraine's civilian infrastructure.
"But no matter how cruel or how much loss of life accompanies it, Russia has singularly failed to break the will of the Ukrainian people or change the policy of its leaders.
"We continue to closely monitor how Russia's long range strike campaign will evolve, as it eats deeper into its strategic reserves of modern missiles. It is notable that Russia are now using the forced labour of convicts to manufacture weaponry. Ukraine, however, continues using its internationally provided long-range artillery to successful effect."
Mr Wallace also said the decision by Russia's Defence Ministry to demote the head of Russian forces in Ukraine after only three months on the job was "certainly significant".
Russia's top military officer – the chief of the military's general staff, General Valery Gerasimov – was named as the replacement for General Sergei Surovikin, who was demoted to deputy earlier this month.
Mr Wallace said there is no loss of momentum from the international community to support Ukraine.
"President Putin believed the West would get tired, bored and fragment. Ukraine is continuing to fight and, far from fragmenting, the West is accelerating its efforts," he said.
The Defence Secretary said the US had invested about $24.2 billion (£19.8bn) in support for Ukraine since the beginning of Russia's invasion on 24 February last year, including thousands of anti-aircraft and anti-armour systems and more recently Patriot air defence battery and munitions, as well as 45 refurbished T-72B tanks and 50 Bradley infantry fighting vehicles to assist with Ukraine’s counter offensive.
He also welcomed the decision of the French government to provide Ukraine with their AMX-10 light, highly mobile, tank.
Mr Wallace said: "As important as these contributions are in and of themselves, what matters more is that they represent part of an international effort that collectively conveys a force multiplier effect. None of this is happening unilaterally. No one is doing this on their own."
He said the "most significant package of combat power to date" would include:
- A squadron of Challenger 2 tanks with armoured recovery and repair vehicles
- A battery of eight AS90 guns "at high readiness" and a further two batteries at "varying states of readiness"
- Hundreds more armoured and protected vehicles including Bulldog
- A manoeuvre support package, including minefield breaching and bridging capabilities worth £28 million
- Dozens more uncrewed aerial systems worth £20 million to support Ukrainian artillery
- Another 100,000 artillery rounds; on top of the 100,000 rounds already delivered.
- Hundreds more sophisticated missiles including GMLRS rockets, Starstreak air defence missiles, and medium-range air defence missiles
- An equipment support package of spares to refurbish up to 100 Ukrainian tanks and infantry fighting vehicles
Shadow defence secretary John Healey said the Government's first package of UK military assistance for 2023 "has Labour's fullest support".
Mr Wallace said that while the tanks and the AS90s would come from UK stocks, along with their associated ammunition, a significant number of the other donations would be purchased from the open market or from supportive third-party countries.
He said the latest package was an important increase in Ukraine's capabilities, adding: "It means they can go from resisting to expelling Russian forces from Ukrainian soil.
"President Putin cannot win but he is equally certain to continue inflicting this wanton violence and human suffering until his forces are ejected from their defensive positions and expelled from the country.
"That requires a new level of support – the combat power only achieved by combinations of main battle tank squadrons, operating alongside divisional artillery groups, and further deep precision fires enabling targeting of Russian logistics and command nodes at greater distance."
The Defence Secretary said that the UK would be the first country to donate Western main battle tanks, saying it was "worth reiterating why we are doing this," adding: "Because in 2023 the international community will not let Russia wait us out while inflicting terrible suffering on Ukrainian civilians. The international community recognises that equipping Ukraine to push Russia out of its territory is as important as equipping them to defend what they already have.
"This week dozens of nations will meet in Ramstein, Germany, to progress further donations and international coordination.
"The Kremlin will be in no doubt that we are resolved to stand by Ukraine in her fight."
Downing Street had earlier expressed confidence that Ukraine would use British tanks effectively after Russia claimed Challenger 2s "will burn just like the rest" when the UK delivers the heavy weapons to the Ukrainian frontline.
No 10 has said there is a "plethora of evidence" showing Mr Zelensky's troops have used UK-supplied weapons successfully and minsters fully expected them to continue.
The Kremlin has sought to downplay the significance of the UK's move to supply increasingly more advanced weapons to aid the resistance.
Spokesman Dmitry Peskov said "these tanks are burning and will burn just like the rest", claiming the supplies were an attempt to draw out the conflict.
But the Mr Sunak's official spokesman said: "We have seen very clearly that the Ukrainian armed forces have been very effective with the equipment that we have provided to them.
"I think there is a plethora of evidence for that and we are confident they will do so again."