Pressure groups said they were surprised by the number of refusals they had received from government departments after they asked to see information made available to the public after the Act was introduced on 1 January.
They said there were "loopholes" protecting publicly funded bodies from replying to questions, adding that Whitehall was less open than quangos, the police and hospitals.
Phil Michaels, head of legal affairs at Friends of the Earth, said yesterday that although the Act could revolutionise the way government operates, there were "cultural blockages" that were preventing information from being released.
"Many of the problems we have encountered relate not to problems with the law but with civil servants' cultural blockages and not understanding the legislation," he said. "We have had three letters from three different sections of the DTI written in identical terms. It's badly written pro- forma letters that don't comply with the legislation. But people should not be put off. They should make more requests and challenge rebuttals."
Heather Brooke, a Freedom of Information campaigner, said the UK authorities were being far less open than in the United States. Ms Brooke, author of a guide to using the Act, Your Right to Know, said she was disappointed by the lack of openness in Whitehall although there were signs that quangos and the police were responding more positively.
The Metropolitan Police had told her the number of attacks in her local London parks. But the Government had refused to tell her how many issues the Attorney General had been consulted about. She said: "There is continuous talks about getting citizens active but they refuse to give out the main tool - information. How can I challenge a hospital closure if I don't have the information about why it is being closed?"
Staff working for political parties and pressure groups contacted The Independent after it reported yesterday how the Government was refusing to disclose information under the Act. Rob Blackie, head of research for the Liberal Democrats, said he even been refused updated information that he had received before the Act came into force.
"They have dragged their heels as far as possible and seem to be hoping to kill these things. Central government is doing all it can to block requests," Mr Blackie said.
The Patients' Association said hospitals were replying to requests for information about MRSA infection rates. But it said it had yet to test the system by applying for prescribing rates of NHS doctors.
The anti-bullying pressure group Bullying Online said it was frustrated that publicly funded bodies were not covered by the Act.
But Maurice Frankel, the director of the Campaign for Freedom of Information, urged people not to be put off if they receive negative responses.
Mr Frankel encouraged people to appeal to the freedom of information commissioner who has the power to force a department to comply.
"You shouldn't write the Act off on the basis of the replies that come back after 20 working days," he said.
"The real test is what happens when you go to the information commissioner."Reuse content