Boris Johnson will on Thursday pledge another 6,000 missiles to Ukraine as Nato countries agreed to send equipment to protect its troops from Russian nuclear and chemical attacks.
The UK is to double its lethal aid by providing further anti-tank and high-explosive weapons, bringing the total to more than 10,000.
An extra £25 million has been pledged for the Ukrainian military on top of the £400 million committed in humanitarian and economic aid.
Jens Stoltenberg, secretary general of Nato, said on Wednesday he expected leaders to agree to extra support, which is likely to include gas masks and protective suits, at an emergency summit in Brussels on Thursday.
Training, respirators, hand-held detectors and mobile decontamination units are also likely to be offered to Kyiv.
“I expect allies will agree to provide additional support, including cyber-security assistance as well as equipment to help Ukraine protect against chemical, biological, radiological and nuclear threats,” Mr Stoltenberg said.
