An extra £1.3bn in military support is to be handed to Ukraine by the UK, in a significant increase in support for the country as it continues to resist Russia’s illegal invasion.

In a package that marks the UK’s highest rate of military spending since the end of the Iraq and Afghanistan campaigns, the funding was revealed before a meeting of G7 leaders to discuss what additional help can be given to Volodymyr Zelenskiy’s forces. Boris Johnson is also due to meet arms companies to ask for an increase in production.

The funding will come from UK reserves after being agreed with the Treasury and will include £300m in military equipment already agreed by Johnson. It includes anti-battery radar systems to target Russian artillery, GPS jamming equipment and night-vision devices.

Equipment dispatched by Britain to Ukraine has already played a significant role in picking off Russian tanks and heavy vehicles. The use of NLAWs, or next-generation light anti-tank weapons, became a feature of the early weeks of the conflict as they were easy to deliver and simple for Ukrainian troops to use.

“Putin’s brutal attack is not only causing untold devastation in Ukraine, it is also threatening peace and security across Europe,” Johnson said. “The UK was the first country to recognise the scale of the threat and send arms to help the Ukrainians defend themselves. We will stand by that endeavour, working with our allies to ensure Ukraine can continue to push back the Russian invasion and survive as a free and democratic country.”

The US president, Joe Biden, has also pledged military help for Ukraine. The next tranche of US equipment will include artillery rounds, counter-artillery radars and electronic jamming equipment. Biden and Johnson will be among G7 leaders holding a virtual meeting with Zelenskiy to mark VE Day and discuss future support.