Defence Secretary Ben Wallace has also invited his Russian counterpart for talks in London.
Britain is providing further “self-defence” weapons and training to Ucrânia amid concerns over a possible Russian invasion.
Defence Secretary Ben Wallace said light anti-armour defensive weapons systems would be supplied to Ukraine, with a “small number” of UK personnel travelling to the country to provide training.
The announcement came after he warned tens of thousands of Russian troops are positioned next to the Ukrainian border, explaining the deployment is “not routine” and they are equipped with tanks, armoured fighting vehicles, rocket artillery and short-range ballistic missiles.
Russia’s presence and levels of readiness are contributing to a “destabilising and coercive atmosphere that risks miscalculation at best and at worst conflict”, Mr Wallace added.
He invited his Russian counterpart, Sergey Shoygu, to visit Londres “in the next few weeks” to discuss “issues related to mutual security concerns and engage constructively in good faith”.
After highlighting previous work as part of Operation Orbital, the UK’s training mission in Ukraine, Mr Wallace outlined new support being provided.
He told the Commons: “In light of the increasingly threatening behaviour from Russia and in addition to our current support, the UK is providing a new security assistance package to increase Ukraine’s defensive capabilities.
“We have taken the decision to supply Ukraine with light anti-armour defensive weapons systems.
“A small number of UK personnel will provide early-stage training for a short period of time, within the framework of Operation Orbital, before returning to the United Kingdom.
“This security assistance package complements the training capabilities Ukraine already has and those that are also being provided by the UK and other allies in Europe and the United States.
“Ukraine has every right to defend its borders and this new package of aid further enhances its ability to do so.
“Let me be clear: this support is for short-range and clearly defensive weapon capabilities; they are not strategic weapons and pose no threat to Russia; they are to use in self-defence.”
Mr Wallace reiterated there is a “package of international sanctions ready to go” should any “destabilising action” by Russia in Ukraine take place.
He noted any invasion will be viewed as an “occupation”, adicionando: “I fear it could lead to a huge loss of life on all sides.
“The current difficult relationship with the Kremlin is not the one we wish it to have with the United Kingdom, it does not have to be this way.”
Mr Wallace went on: “We wish to be friends with the Russian people as we have been for hundreds of years. And there is a world in which we can establish a mutually beneficial relationship with Russia.
“I still remain hopeful that diplomacy will prevail. It is President Putin’s choice whether to choose diplomacy and dialogue, or conflict and the consequences.”