Former British Prime Minister Boris Johnson on Thursday urged allies to double down on sending military equipment to support Ukraine and speed up an end to the war with Russia.

Johnson, who left office in September 2022 amid a wave of scandal, was leading Britain when Russia invaded Ukraine in February and in subsequent weeks sought to position Britain as Ukraine's number one ally in the West.

"There is nothing to be lost by doubling down on the material, equipment that we are sending to Ukraine and there is nothing to fear in escalation, and the best thing for the world is to get this thing done, and done fast," Johnson said in an interview as part of the Reuters Impact Arctic Warning series on the sidelines of the World Economic Forum (WEF) in Davos.

"That is the cheapest solution. It's the solution that has the lowest cost in human life and suffering."

Johnson was speaking at Ukraine House, an exhibition front on Davos' main high street, where Ukraine's high-level delegation has been drumming up support for the country as it nears the end of the first year of the war.

The former mayor of London was made an honorary citizen of Ukraine's capital on Wednesday night by Kyiv's mayor Vitali Klitschko in Davos.

Waving his residency card proudly, Johnson said it would be his "golden Oyster card" - a reference to the travelcard used in London - to one day return to the Ukrainian capital, although he had no immediate plans to go.

"I hope one day I will be able to use it," he said, adding that he had great relations with Ukraine President Voldomyr Zelenskyy.

Johnson dismissed suggestions that his activism on Ukraine could be seen as undermining current British Prime Minister, Rishi Sunak, as he ramps up military support.

Britain this week said it would supply Ukraine with 14 Challenger 2 main battle tanks - the first modern Western tanks to be promised to Kyiv - and other heavy weaponry.

"I’m a humble backbencher and I’m backing my government which remains wholly supportive of Voldomyr Zelenskyy, and the Ukrainian people and where I can be useful is keeping the narrative up and reminding people," he said.

Johnson, who was also prime minister when a deal was struck in Glasgow in 2021 to combat climate change, added that the war in Ukraine should not be used as an excuse to go back on pledges.

"It was a big moment and then Ukraine happened and everybody panicked and thought we had we gone too far, too fast," he said.

Johnson said the world should not reverse course, but press ahead with new green technologies, such as wind and nuclear power, and that the results would eventually appear.

"You have to overcome people's skepticism," he said. "You have to show them that green agenda is going to bring their bills down and if we hadn't put in the offshore wind in the United Kingdom the impact of what (Russian President Vladimir) Putin did would have been far worse."

When asked whether one day he could see himself wandering the WEF again as British Prime Minister, Johnson remained diplomatic saying he was more than happy representing his constituents as a member of parliament.

"I'm having a very happy and productive time getting on representing Uxbridge and South Ruislip and doing some things I care about, amongst them Ukraine, which is very important," he said with a wry smile.