Ukraine is “humbled” by the more than 150,000 Britons who have expressed an interest in housing refugees fleeing Russia’s invasion, the nation’s ambassador to the UK said.

Vadym Prystaiko said it has been a “bumpy ride” getting the Government to set up visa-free travel since Russian president Vladimir Putin launched his war, but welcomed the Homes for Ukraine scheme as it opened for refugee applications on Friday.

Concerns have been raised about the programme’s bureaucracy, safeguarding and resourcing as Ukrainians are matched with British sponsors.

But the ambassador is cautiously optimistic, saying “this is a temporary solution but I hope it will work” as they work on details including school places and jobs, and is hopeful any issues linking refugees with homes can be “remedied quite soon”.

In an interview with the PA news agency, he said: “We’re in an initial stage of this work but I’m very grateful that the UK Government and citizens are opening up their hearts, and sometimes homes, offering Ukrainians to stay here.

“I’m humbled by the sheer number of people who are opening up, sometimes just saying, ‘I have a spare room, it’s not even a spare house, or flat, it’s just a spare room.’ This is something that’s very unusual.”

Speaking from the Ukrainian embassy in west London, Mr Prystaiko said that in his discussions with ministers he broadly estimates that between 100,000 and 200,000 Ukrainian will want to temporarily seek refugee in the UK.

More than 150,000 people in Britain had registered their interest in the scheme by Thursday, and refugees who have found a sponsor could start applying on the Government website from Friday.

Those with valid passports who apply under the scheme will receive a permission letter from UK Visas and Immigration (UKVI) confirming that they can travel to the UK.

Mr Prystaiko also sounded an alarm on Ukraine’s need for further humanitarian aid, as the Kremlin’s troops surround major cities and bombard them with missiles.

And he warned the war could have further effects on the world’s food supplies.

“Ukraine is a major agricultural producer in the world, if we don’t start planting the grains the world will feel it quite soon, at the end of this year this ripple effect… there will be not enough food not just for Ukrainians, Ukrainians will survive, but for the rest of the world…” he said.

“Things like that have to be thought of right now. And humanitarian, the breadbasket of Europe now is begging for food. This is an effect the war is having right now on us.”

He welcomed Britain sending defensive weapons but said “we need much more stuff” as he continued talks with ministers.