Thousands of UK citizens are believed to be in distress while they are stranded in South Africa but the government refuses to relax lockdown regulations to allow the European country's crews to rest before returning home.
"South Africa has been clear that it's a red line for them. They are not prepared to relax that requirement at the moment," UK High Commissioner to South Africa Nigel Casey said.
Two weeks ago, South Africa put in place a travel ban on countries hard hit by the global coronavirus pandemic, which included Germany, China, Italy, the US and the UK.
Tighter measures were put in place after President Cyril Ramaphosa announced on Monday that the country would go into lockdown to curb the spread of the virus.
The lockdown includes closing off the country's ports and only permitting the movement of essential goods.
But Casey told News24 that the regulation refusing crews entry into the country was at odds with international flying time regulations that airlines should ensure that crews have mandatory rest periods.
"If they come all the way from a European airport, they are obliged to rest for a minimum period, which means an overnight stay in a hotel, which is completely what they would be doing under a normal schedule. That is no longer possible and that has created a very large practical obstacle," Casey said.
He said while South Africa had agreed, in principle, to assist with the evacuation of UK citizens, its refusal to relax regulations meant they had to look for creative approaches to solve the problem, but added that none were good enough.
Casey said airlines were not keen to allow "double crews" in which one pilot rests during the flight to South Africa and later takes over, while another rests on the way back.
He added that proposed ideas for stopovers at other African hubs could lead to complications, saying that rules changed constantly while countries tried to fight the pandemic.
"We would rather have a reliable direct route which we can have confidence in, which the passengers can have confidence in to get them back home," said Casey.
He also committed to continue discussing the issue with South Africa about the matter.
However, Transport Minister Fikile Mbalula has insisted that no crews are allowed to get off planes.
"The planes that come in, we said the crew does not disembark. If you disembark, you are going to infect us. Come with a crew that is able to change, meaning when you land, someone else must be able to take over," he said.
He said South Africa issued a notary of its decision and that countries seeking to evacuate their citizens should come prepared.
"Our own crew was not allowed to disembark in Wuhan. Our people came straight into the airline and we came back home. Crews changed on board," said Mbalula.
He said only the Philippines allowed a stopover.
"People want normal luxury," he said.
During a media briefing on Friday - the first day of the 21-day lockdown, Mbalula said several countries were involved in discussions with South Africa about collecting their citizens.
Germany is expected to fetch its citizens next week, he said.