Prime Minister David Cameron today promised to look into the case of three people who were arrested after information about the expenses of Cumbria's Police and Crime Commissioner was leaked to the local press.
He said that in general whistleblowers should be supported and he would "look carefully" at the issue.
Conservative Police and Crime Commissioner Richard Rhodes has apologised for failing to check the near £700 cost before hiring a chauffeur-driven Mercedes to go to two evening engagements and for not publishing his expenses online as he should have done.
Cumbria Police has searched one property and arrested three people, two of them civilian workers for the force, after the cost of the car hire was leaked to weekly newspaper the Cumberland and Westmorland Herald. Photocopies of the invoices are also believed to have been sent to the Carlisle News and Star.
The Cumberland and Westmorland Herald has been visited twice by police and asked to reveal its sources, which it has refused to do.
Editor Colin Maughan told Pres Gazette: “The vast majority of people in Cumbria support what we did and think the reaction that it produced is outrageous.”
The issue was raised today at Prime Minister's Question Time by Liberal Democrat party president Tim Farron, who said: "Last week three people in Cumbria were arrested for apparently blowing the whistle in the public interest over the actions of the police commissioner.
"Will you agree with me that this is a threat to freedom of speech, an outrage in a democratic society and will you intervene to make sure there is an independent investigation?"
The Prime Minister told him: "I will look carefully at this case. In general we should support whistleblowers and what they do to help improve the provision of public services. I will have a look and get back to you."