Guardian journalist Amelia Hill (top) has been questioned by police officers investigating alleged leaks of information from the Operation Weeting investigation into phone hacking at the News of the World, the paper said today.
Hill was questioned under caution several days ago in a case that has raised concerns about attempts to criminalise contact between journalists and off-the-record sources.
A spokesperson for the Guardian said in a statement: "We can confirm Amelia Hill has been questioned in connection with an investigation into alleged leaks."
They added: "On a broader point, journalists would no doubt be concerned if the police sought to criminalise conversations between off-record sources and reporters."
Michelle Stanistreet, NUJ general secretary, said: "There is a vital journalistic principle at stake here. It is outrageous that an allegation of off-the-record briefings is being treated as a criminal matter. There is a clear distinction between legitimate off-the-record interviews and the illegitimate payment of bribes.
“In this case the allegation is simply that a Scotland Yard detective is an off-the-record source. There is no suggestion of bribery or corruption and there is no suggestion that anything said by the source threatened national security, jeopardised the course of the hacking inquiry, or invaded anybody's privacy.
“No employer likes an employee to talk to the press without permission. In this case the police appear to be using the criminal law at their disposal rather than simply resorting to internal disciplinary proceedings. Using criminal law as a weapon to silence people in the workplace is highly inappropriate.
“Good journalism depends on off-the-record sources and as journalists our sources are sacrosanct. We don't want to live in a society in which the only information from the police is the official line authorised by the commissioner or an official press release. Any threat to the protection of sources is a direct threat to citizen’s right to know and absolutely not in the public interest.”