Ministers are pressing ahead with plans to limit the Freedom of Information Act which critics say is aimed at keeping embarrassing information secret.
FOI requests cost central government nearly £25m a year
The government answers requests which cost less than £600 to process - but the proposals would include officials' time in that limit.
Critics say it will mean a massive reduction in information disclosed on cost grounds.
The government has said the changes could save £5m of taxpayers' money.
A review of the impact of the act found requests cost central government £24.4m a year and other public authorities £11.1m a year.
Lord Falconer, the Lord Chancellor, has issued a consultation paper which proposes extending the £600 limit to include officials' time.
It would also mean several requests by one company, organisation or individual - even if they are on different subjects - could be dealt with together.
The paper confirms the proposals would particularly impact upon MPs, journalists, campaign groups and researchers.
The paper also says journalists make 10% of FOI requests to central government, which use 20% of officials' time.
Information Rights Minister Baroness Ashton said the changes would allow public authorities to consider the work involved in dealing with requests in a sensible way.
"The Freedom of Information Act has benefited the people - that's what it was intended for - and we must continue to build on its success," she said.
"However, in light of experience we feel that the existing provisions need to be extended to make sure public authorities can strike the right balance between access to information for all and the delivery of other public services."
But Campaign for Freedom of Information director Maurice Frankel has argued that ministers chose to involve themselves in potentially "newsworthy" requests - and their time was the most expensive.
He told the BBC in October: "By doing this, what they are actually going to do is make it much easier for authorities to refuse on costs grounds.
"It would reduce the amount of politically sensitive and politically embarrassing information that would be disclosed."