Labour has called on the Government to scrap its review of the Freedom of Information (FOI) Act, accusing David Cameron of trying to avoid public scrutiny and "govern from the gloom".
In a speech in London today, Labour's deputy leader Tom Watson will say that the Act should instead be strengthened and extended to give voters greater rights to see what the Government is doing.
He will say that he suspects the six-person commission looking at the balance between transparency and official secrecy is "predestined" to deliver the conclusion which the Government wants and which will allow ministers to raise barriers to obtaining information.
The commission - which includes former home secretaries Jack Straw and Lord Howard - has been criticised for the absence of freedom of information campaigners among its members.
Former head of the civil service Lord Kerslake last week dismissed claims that the Act had a "chilling effect" on civil servants, insisting that the greater challenge to Whitehall's operations was the "routine" leaking of information by special advisers and ministers.
Mr Watson is expected to say: "I am calling on the Government today to abandon its review.
"It doesn't have the support of the public. It is opposed by many of the organisations that are covered by FOI; it has been condemned by the Information Commissioner and slammed by a former head of the civil service.
"It's a waste of taxpayers money and it's time it was scrapped. The Freedom of Information Act works well. Labour would strengthen and extend it."
Mr Watson will accuse the Government of seeking to "reverse the transparency Labour introduced" and to "turn off the lights, systematically making it harder for people to engage with policy making, retreating into a darker and more secretive place".
Having promised in opposition that Tories would "bring the operation of Government out into the open", as Prime Minister Mr Cameron "wants to govern from the gloom in the old-fashioned way, without the inconvenience of scrutiny", Mr Watson will say.
He will cite NHS England's announcement that weekly bulletins on the health service's performance over the winter will no longer include figures on four-hour waits in emergency departments, the number of ambulances queuing outside hospitals or operations cancelled at the last minute.
Mr Watson will argue that "a more open government will be a better government, with more robust policy making".
And he will say that this will be all the more important over the coming 30 years, when technological developments are likely to lead to new forms of state intervention in ordinary people's lives which will require new safeguards to protect citizens from erosions of their civil liberties.