Defence secretary Ben Wallace launched a withering rebuke against activist Pen Farthing's claims his charity's animals were blocked from leaving Afghanistan.
Ex-Royal Marine Farthing, 52, who founded the Nowzad shelter in Kabul and is seeking to secure the passage of 173 dogs and cats out of the country, said he had been stuck outside Kabul Airport for 10 hours.
Farthing had added that his team were being denied entry to the airport and even pleaded directly with the Taliban's spokesman to gain safe passage.
But Wallace insisted that 'no one... had blocked a flight', before describing the claim as a 'total myth'.
The defence secretary went on to indirectly accuse Farthing's group of 'bullying, falsehoods and threatening behaviour towards MoD personnel' as the diplomatic row continued.
Mr Wallace tweeted: “Let’s get some facts out there: 1. No one , at any stage has blocked a flight. This is a total myth and is being peddled around as if that is why the pet evacuation hasn’t taken place. 2. I never said I would not facilitate. I said no one would get to queue jump.
“3. The issue, as those desperate people waiting outside the gates know too well, has always been getting processed through the entrances. It can take over 24hrs. There is no point turning up with a plane until the passengers / pets are airside.”
He added: “The bullying, falsehoods and threatening behaviour by some towards our MOD personnel and advisors is unacceptable and a shameful way to treat people trying to help the evacuation. They do their cause no good.
“So can people now please let my civil servants and military get on with dealing with one of the most dangerous and challenging evacuations for a generation. As professionals they will do their best for all those eligible and with my full support.”
Paul Farthing, known as Pen, founded the Nowzad shelter in Kabul after serving with the British Army in Afghanistan in the mid-2000s, with the organisation rescuing dogs, cats and donkeys.
Since the collapse of the Afghan government, he has campaigned to have his staff and their families as well as 140 dogs and 60 cats evacuated from the country in a privately chartered Airbus A330.
On Tuesday, Wallace had cleared the path for Farthing, his staff and animals, saying officials would seek to facilitate their departure aboard the chartered aircraft if they arrived at Kabul Airport.
But on Thursday morning Farthing said his team were being denied entry and pleaded with the Taliban to allow them through to get on the plane.
Addressing Taliban spokesman Suhail Shaheen, Farthing tweeted: “Dear Sir; my team and my animals are stuck at airport circle.
“We have a flight waiting. Can you please facilitate safe passage into the airport for our convoy?
“We are an NGO [non-governmental organisation] who will come back to Afghanistan but right now I want to get everyone out safely.”
Watch: Minister warns of potentially 'very imminent' terror attack in Kabul
Farthing added: “We have been here for 10 hours after being assured that we would have safe passage.
“Truly would like to go home now.”
Speaking to The Sun, Farthing said the situation was "getting really desperate" and that the team had "hours" before their animals start dying.
He added: “We are in touch with the British forces but they say they are powerless to help.”
The evacuation has been made more urgent after a minister warned that a “highly lethal” terror attack could strike Kabul within hours.
Armed forces minister James Heappey warned on Thursday that there is “very credible reporting” of an “imminent” and “severe” threat to Kabul Airport.
He called on those queuing outside Hamid Karzai International Airport to move to safety amid concerns over an affiliate of the so-called Islamic State in Afghanistan, know as Isis-K, an enemy of the Taliban.
The threat is heaping extra pressure on the operation to help people flee the nation captured by the Taliban, with Tuesday’s deadline for foreign troops to leave fast approaching.
Mr Heappey told BBC Breakfast: “The credibility of the reporting has reached the stage where we believe there is a very imminent, a highly lethal, attack, possible within Kabul.
“And, as a consequence, we’ve had to change the travel advice to advise people not to come to the airport, indeed to move away from the airport, find a place of safety and await further instruction.”
Defence secretary Wallace held a briefing with MPs on Wednesday, where he is reported to have said it would be a “better option” for those who still need to leave the country to travel across the border.
Colonel Richard Kemp, former head of British forces in Afghanistan, said this morning that the threat of a terrorist attack at Kabul Airport “has existed right the way from when this evacuation began”.
He told BBC Breakfast: "There could be a terrorist attack of some sort against the forces in the airport, maybe forces outside the airport, and of course the people trying to get in.”
Farthing’s campaign to flee Afghanistan was given a boost on Wednesday when Wallace authorised the Ministry Of Defence allow Farthing and his staff on board the chartered aircraft, along with the animals.
Farthing previously said the animals would be transported in the aircraft’s hold and that once his staff were accommodated any spare seats on the plane could be filled by other people cleared for passage by UK authorities, with the flight able to take 250 passengers in total.
Latest figures from the Ministry of Defence (MoD) showed that 11,474 people had been able to leave Afghanistan since the evacuation mission Operation Pitting began on 13 August.
But the end of the operation is rapidly approaching after US president Joe Biden rejected calls from Boris Johnson and other allies to delay his 31 August withdrawal date for the remaining US troops, who are providing security at Kabul airport.
Watch: Latest Afghanistan evacuation flight lands in UK