Former prime minister Tony Blair has been criticised for failing to cooperate with a report into the Freedom of Information Act.
Sir Alan Beith, chairman of the Commons justice select committee, said the former Prime Minister was given every chance to give evidence at a convenient time but only answered written questions after a press report suggested they would be critical of his non-appearance.
"We deplore Mr Blair's failure to cooperate with a committee of the House," Sir Alan said.
Blair insisted that the the Act "undermined discussions at the highest levels of government." He claimed he was a "nincompoop" for his role in the FOI legislation, which was introduced by his government.
The findings of the report were finalised before the MPs received a letter from Mr Blair and made no major recommendations to reduce the openness created by the Freedom of Information laws.
It did not recommend fees should be brought in to recoup the costs of answering requests.
Sir Alan said: "Former prime minister Tony Blair described himself as a 'nincompoop' for his role in the legislation, saying that it was 'antithetical to sensible government'.
"Yet when we sought to question Mr Blair on his change of opinion he refused to defend his views before us and submitted answers to our written questions only after our report was agreed, and after a press report had appeared, suggesting we might criticise his failure to give evidence."
Blair said he stood by the "somewhat colourful explanation of my views in my biography".
The report said the existing legislation already intended to provide a "safe space" for policy-making in which ministers could be given frank advice by officials and this should be respected by everyone.
Ministerial vetoes would, from time to time, need to be used to protect this space, the report added.
It said the "potential risks of a chilling effect - if it is a reality - go beyond a bowdlerising or editing of the records".
"It is that no record exists, because ministers may avoid holding formal meetings entirely," the committee said.
But research by the Constitution Unit found the "chilling effect" of FOI laws appeared "negligible to marginal", despite the concerns raised by former senior ministers and officials.
Retired Cabinet Secretary Lord O'Donnell told the MPs that ministers and officials "are going to find ways around it, things are not going to be written down" and the cost of ministers' mobile phone bills will rise.
"That, to me, makes for worse government and it makes it impossible for (historians) to try to recreate accurately what has gone on when there are no records," he warned.
The MPs' report concluded: "Given the uncertainty of the evidence we do not recommend any major diminution of the openness created by the Freedom of Information Act.
"But, given the clear intention of Parliament in passing the legislation that it should allow a 'safe space' for policy formation and Cabinet discussion, we remind everyone involved in both using and determining that space that the Act was intended to protect high-level policy discussions.
"We also recognise that the realities of government mean that the ministerial veto will have to be used from time to time to protect that space."
Sir Alan added that, overall, the Act "enhanced the UK's democratic system and made our public bodies more open, accountable and transparent".
"It has been a success and we do not wish to diminish its intended scope, or its effectiveness," he said.
The report also found that while FOI imposes costs, "it also creates savings when the inappropriate use of public funds is uncovered - or where fear of disclosure prevents the waste of public money".
"Evidence we have seen suggests that reducing the cost of FOI can be achieved if the way public authorities deal with requests is well thought through," Sir Alan said.
"Complaints about the cost of FOI will ring hollow when made by public authorities which have failed to invest the time and effort needed to create an efficient Freedom of Information scheme."
The report also called for higher fines for the destruction of information, along with changes to protect universities from having to disclose research before the paper has been published.
Dr Wendy Piatt, director general of the Russell Group, backed the report, saying that if research data was not exempt from FOI legislation "then we are in real danger of killing the goose that lays the golden eggs".
"Openness and transparency must have limitations in order to protect our national interests, including national security and the safety of our researchers."
Nick Pickles, director of the civil liberties campaign group Big Brother Watch, added: "Access to information is an essential part of holding government to account.
"As the committee has found, the Act already protects sensitive discussions and those seeking to restore a veil of secrecy to decision making should not be allowed to stem the flow of information, by charging or limiting the scope of the Act.
A spokesman for Mr Blair's office said he had submitted written evidence to the committee in response to its questions.