Boris Johnson is facing growing anger over his plans to travel the globe in a red, white and blue jet at a cost to the taxpayer of almost £1 million.
Opposition MPs accused the prime minister of an “utterly unacceptable use of public funds”.
Ed Davey, the acting Liberal Democrat leader, said ministers could have used the money to buy 180,000 doses of a new Covid-19 wonder drug instead.
The RAF Voyager, a military plane used by the prime minister, is being rebranded at an airport in Cambridge.
Downing Street say the final cost of the resfresh, designed to “promote the UK around the world”, will be around £900,000.
The move comes two years after Mr Johnson questioned the colour of the paint job on the Voyager and said he needed his own plane to help the UK strike post-Brexit trade deals.
The then foreign secretary suggested he and other cabinet ministers should have another aircraft, alongside the one often used by the prime minister.
He said: “What I will say about the Voyager, I think it's great, but it seems to be very difficult to get hold of... I don't know who uses it, but it never seems to be available.”
Mr Johnson also said it was “'striking” such a plane did not yet exist and suggested that it could be a different colour than grey.
Downing Street said the rebrand was “in line with many other leaders’ planes”.
The aircraft will continue to be known as the RAF Voyager and to be used by both the royal family and prime minister, No 10 said.
Asked about the plane, the prime minister’s spokesman said: “We expect the cost to be around £900,000. That incorporates the cost of creating a design that will promote the UK around the world without compromising the plane’s vital military role. At every stage we worked to ensure value for money for the taxpayer and all the work has been undertaken in the UK, directly benefiting British suppliers.”
Stewart McDonald, the SNP MP for Glasgow South, said the rebrand was “an utterly unacceptable use of public funds whilst members of the armed forces are spending their own money on uniforms and kit, and the equipment plan deficit is well into the billions for several years running.”
Sir Ed pointed out that the drug dexamethasone, which researchers announced this week can potentially save the lives of some patients with coronavirus, costs £5 per person treated.
Layla Moran, the Lib Dem education spokesman, said: "This is a colossal waste of taxpayers' money. The same money could be spent providing an extra £15 school meals voucher to 60,000 children.
"Boris Johnson has insulted our closest allies, scrapped the foreign aid department and is ploughing ahead with a self-destructive no deal Brexit. Repainting his plane won't undo the damage he's done to the UK's reputation abroad.
Louise Haigh MP, Labour’s Shadow Northern Ireland secretary, was equally scathing.
“When families across the country are worried about their jobs, health and the education of their children, they will rightly question the Government’s priorities when they are spending almost a million pounds redecorating a plane which in all likelihood has been grounded for months because of the coronavirus,” she said.
Her party colleague Justin Madders tweeted: "What's he painting it with, gold leaf?"
