The series, which began on Monday, stars Hugh Bonneville and Jessica Hynes as members of the organising team preparing for the Olympic Games.
Australian writers John Clarke and Ross Stevenson have now told the Sydney Morning Herald that they believe the show is based on their series The Games, which ran in 1998 and 2000. The pair also pitched the format to the BBC with the help of Kath And Kim producer Rick McKenna.
Clarke and Stevenson alleged that Twenty Twelve writer John Morton had been given DVDs of their series and suggested that the claims of plagiarism are "very sound".
"We haven't seen Twenty Twelve so it would be unreasonable of us to make an accusation of copying, but it's pretty clear where they got the format," Clarke said. "It is a serious issue for us. We worked very hard on that project and we had long conversations with these people who've now done a show like that in Britain."
However, a spokesperson for the BBC strongly denied the accusations of plagiarism.
According to The Guardian, the representative said: "Twenty Twelve is an original and distinctive comedy series looking at London as it counts down the last 1000 days before the 2012 games begin. It is written by John Morton who wrote People Like Us and Broken News for the BBC. Its comedy is delivered through a distinctively British sense of humour."
She added: "We have investigated the complaints made in relation to The Games and have found no evidence to support the allegations of copying. No use has been made of any material deriving from The Games and we are confident that the allegations are without foundation. We don't dispute that we had contact with Mr McKenna but we maintain that Twenty Twelve is an entirely original series. After a thorough legal assessment we are confident that there is no basis to [the] allegations."
Twenty Twelve continues on Monday at 10pm on BBC Four.