Strict caps on international arrivals have left around 30,000 Australians stranded in the UK and unable to return home, a group of airlines say.

It is essential to help Australians camped out at Heathrow airport in London, the Board of Airline Representatives of Australia (BARA) says in a statement on its website.

It is calling on Australian authorities to increase their quarantine capacity to allow more residents to return.

Currently around 4,000 Australians are allowed back into the country per week, but Prime Minister Scott Morrison says he wants to increase that to 6,000 weekly, ABC News reports.