In a letter to The Sunday Telegraph, Davies claims some people "in and around the government" have tried to influence the BBC's governors by placing them "under public attack".
The letter reads: "The dogged independence of the board in the face of intense pressure has driven some political figures close to distraction, such has been their determination to influence the editorial decisions of Britain's most trusted provider of news and current affairs."
He claims the governors have received veiled and not-so-unveiled threats that the broadcaster's funding, and even director-general Greg Dyke, could be removed.
Davies went on to argue that it is this type of action that justifies the BBC's status as a public service broadcaster.
"All this amply demonstrates why Britain still needs the tried-and-tested system of BBC governance to stand up to storms of this kind," he said.
The BBC governors are appointed by the secretary of state for culture media and sport, currently Tessa Jowell. Davies' letter suggests that the government's friends "appear to have lost confidence in the judgement and honesty of these appointees" and would happily replace them with the commercial industry regulator Ofcom.
"Our integrity is under attack and we are chastised for taking a different view from that of the government and its supporters," said Davies. "Because we have had the temerity to do this, it is hinted that a system that has protected the BBC for 80 years should be swept away and replaced by an external regulator that will 'bring the BBC to heel'."
This is believed to be the first time a BBC chairman has launched such a scathing attack on the government of the day.
It will stoke the already blazing row between the two that was made worse by the death of Ministry of Defence adviser professor David Kelly, who was revealed as the source of BBC reports that accused the government of "sexing up" a dossier on Iraq's weapons of mass destruction, used by the government as part of its argument for war.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the Forum here.