Senior mandarins' warnings about the Freedom of Information Act could fuel "bad behaviour" in Whitehall, the information commissioner has said.
Christopher Graham told MPs that claims there was "no hiding place" from FOI could encourage staff to use private email for official communications.
Former Cabinet Secretary Lord O'Donnell has argued that FOI could have a chilling effect on Whitehall advice.
Mr Graham said that fear was "greatly overdone" and could be "very damaging".
Lord O'Donnell, who was the UK's most senior civil servant until he retired last year, also gave a strong defence at an information tribunal that week of the government's refusal to publish a risk assessment of its controversial NHS overhaul.
He and the Department of Health's top civil servant Una O'Brien argued that many civil servants were worried about their confidential advice to ministers, when it could potentially be published under FOI laws.
But Mr Graham told the committee that in most FOI cases, the line was "overwhelmingly drawn in favour of protection" of public policy.
He said predictions from mandarins that FOI rulings could have a "chilling effect" where nothing got written down were "greatly overdone and to some extent, self-fulfilling".
Claiming there was no hiding place from FOI was "simply not true" and could be "very damaging", Mr Graham said, adding: "It suggests to more junior staff that it would be unwise to keep a proper record and that it's acceptable to use your Gmail account."
The information commissioner also told the committee, amid warnings of more "oral government" should officials stop writing things down, that "sofa government well pre-dated the Freedom of Information Act".
It was not something that had been limited to the previous government, he said. His office was investigating a number of complaints where people had been told the information they requested did not exist, when they had reason to believe it did.
Official business carried out via people's private email accounts still came under FOI and if it was not being properly considered for release, "frustrating" the FOI Act, it could potentially be a criminal offence, he said.
If it turned out that "enthusiastic special advisers" were "communicating through a back channel, this could become quite serious".
Mr Graham said: "The contributions of senior mandarins asserting that there is no hiding place [from FOI] is driving this sort of bad behaviour", adding that with the balance of FOI decisions supporting privacy, "this nonsense shouldn't be going on".
Conservative MP Ben Gummer asked about last week's ruling, ordering the government to publish the transitional risk register for its NHS overhaul. He argued departments could stop drawing up full risk registers "because they know that Doomsday scenarios that have to be considered will be published".
The MP suggested the commissioner's office wanted "to see the world as they would like it to be... and not as it is" and the risk assessment's publication would "skew debate to the point where public discourse becomes unbalanced".
But Mr Graham told him: "I leave the politics to you. You say debate is skewed but the debate will rage. Politicians on each side will explain, gloss, whatever. The risk register is simply whatever the risk register was at the time it was requested - I'm sure politicians on both sides will be able to attack or explain it."
Prime Minister David Cameron has suggested the FOI Act "furs up" the arteries of government. He has argued that the publication of detailed spending breakdowns, public service outcomes and crime maps represents "real" freedom of information.
But Mr Graham told MPs: "I don't think we have to choose between democratic accountability or what the prime minister described as bureaucratic accountability. It's not either/or. It's both."
He said there was "a gap between the rhetoric of openness and the reality of reluctance" and said open data and transparency had to go "hand in hand" with FOI: "Otherwise you are simply defining the public interest as the government's interest and they are not always the same thing. The Freedom of Information Act is always going to be troublesome but it's troublesome in a good cause."
Former Labour PM Tony Blair also expressed frustration at the FOI Act writing in his memoirs that he was an "idiot" for introducing it: "For political leaders, it's like saying to someone who is hitting you over the head with a stick, 'Hey, try this instead', and handing them a mallet."