The former Royal Marine who founded an animal shelter in Afghanistan has apologised for the “incredibly embarrassing” language he used in a voicemail to a government aide as he tried to leave the country.

Paul “Pen” Farthing arrived at London Heathrow on a privately-funded charter flight from Kabul at around 7.30am on Sunday – with about 170 dogs and cats on board.

His Operation Ark campaign to evacuate the rescue animals and staff at his charity Nowzad has been widely covered in the media in the days since the Taliban took back control of Afghanistan.

Members of the government have criticised the animal rescuer for “diverting” efforts to evacuate all British nationals and eligible Afghans before the US-imposed deadline.

Following a number of outbursts on social media, Mr Farthing was recorded shouting at Peter Quentin, who works as a special adviser to Defence Secretary Ben Wallace, in a voice message.

The recording, which was obtained by The Times, accuses the minister and his aide of “blocking” his evacuation flight.

On Monday, Mr Farthing apologised for his “colourful language”.

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He told ITV’s Good Morning Britain: “I’m incredibly embarrassed about my language, I do apologise to everybody who’s listened to that.

“I was at the lowest point I could possibly be. I understand how the world works but emotions got the better of me, so for all those who had to listen to that I do apologise for my language.

“I should not have said it like that, but the sentiment, yes, I was just incredibly upset, angry, frustrated, it was the lowest point. I had no other option, I didn’t know what else to do.”

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Mr Farthing announced his arrival back in the UK on Sunday morning, adding that he was unable to bring back the 24 charity workers and dependents he had wanted to.

Dominic Dyer, a friend and animal welfare campaigner, said the former British soldier was forced to travel back from Kabul alone after being told it was not possible to find people to fill the plane’s seats.

He said the shelter staff were “still in their homes” and that efforts would be made to try to get them out of Afghanistan.

Mr Farthing said he had “mixed emotions” as he touched back down in the UK.

“Arrived Heathrow with partial success of #OpArk,” he tweeted.

“Mixed emotions and true deep feeling of sadness for Afghan today.”

Mr Farthing said his team made it inside the airport perimeter on Friday after the suicide bomb attack that killed more than 90 people in Kabul on Thursday.

But he said he was turned away after US President Joe Biden had changed paperwork rules two hours earlier.

Mr Dyer said an appeal was made to the UK government “to see if we could fill seats with refugees within the airport”, but the response was that “there was no one they could find”.

The former Royal Marine, originally from Dovercourt in Essex, set up the Nowzad animal shelter in Kabul after serving in Afghanistan in the mid-2000s.