A former Royal Marine turned animal welfare charity boss in Afghanistan has urged the public to “get behind the Prime Minister” as he seeks to persuade Joe Biden to keep the Afghan air corridor open.

There are fears that the last evacuation flights could leave the country on August 31 as the Taliban tighten their grip, leaving thousands of vulnerable people with no means of escape.

Paul Farthing, known as “Pen”, founded the Nowzad animal shelter in Kabul rescuing dogs, cats and donkeys after serving with the British Army in Afghanistan in the mid-2000s.

Since the collapse of the Afghan government, he has been campaigning to have all of his staff and their families, as well as his 140 dogs and 60 cats, evacuated from the country in a plan he has dubbed “Operation Ark”.

On Monday morning, a jubilant Mr Farthing announced the UK Government has granted visas for all of his staff and their dependents.

In a video posted on Twitter, Mr Farthing told his 28,000 followers: “I need you to do a couple of things for me, please send Boris Johnson some love.

“I don’t care what party you support, he is behind Operation Ark 100%, he has also granted visas for our 68 staff – that’s absolutely fantastic, cheers prime minister – I owe you a pint.”

He continued: “So, everybody get behind him now, thank him, and also help him out – he needs help convincing Joe Biden to keep this air corridor open.

“The British want to stay, they want to get the job done but Joe Biden is going to force everybody’s hands again just like he did when he deserted this country.”

Mr Johnson is due to chair a meeting of the G7 on Tuesday.

Mr Farthing urged the public to message Mr Biden on every social media platform they have to tell him to keep Kabul airport open.

“Let’s get behind the British Prime Minister, he’s doing the right thing, he’s trying to force Joe Biden to keep this open so let’s get behind him,” he said.

He finished: “Thanks everybody, love you to bits. Let’s get this done this morning.”

Mr Farthing previously managed to get his wife and his heavily pregnant shelter manager out of the country, but warned the latter is now stranded in a “hell hole prison camp” in Germany.

Mr Farthing said that despite being a US citizen who left on an American evacuation flight, she is now with 9,000 other refugees in a camp which he said does not have enough food supplies or toilets.

He told PA: “The west created this and I truly believe that getting my country manager out of Afghanistan was the right thing to do because I thought she’d be treated with dignity and a little bit of priority because she’s 33 weeks pregnant.

“But to see her now trapped in a hell hole prison camp … I can’t express how angry, upset, disappointed and disillusioned I am.

“She doesn’t even know exactly where she is right now.”

He added: “She’s scared, because what happens if she has the baby in that camp – have they got the right facilities, have they got anything set up, and what if there’s complications?”

The rest of the Nowzad team, including Mr Farthing, are due to fly out from Kabul in the coming days, if they can get through the chaos at the airport, his campaigner Dominic Dyer has said.