The detention and subsequent criminal investigation into the partner of a Guardian journalist threatens to undermine the position of the free press around the world, the editors of several northern European newspapers have warned.
In an open letter to British Prime Minister David Cameron, the editors of Denmark's Politiken, Sweden's Dagens Nyheter, Norway's Aftenposten and Finland's Helsingin Sanomat describe the detention of David Miranda, partner of the Guardian's Glenn Greenwald, as harassment.
They say that the "events in Great Britain over the past week give rise to deep concern" and call on the British Prime Minister to "reinstall your Government among the leading defenders of the free press".
Miranda was detained by the London Metropolitan police for nine hours as he was passing through Heathrow on his way to Brazil.
Greenwald has broken a series of stories about the US intelligence agencies based on material leaked by the National Security Agency whistleblower Edward Snowden.
The editors describe a free press as crucial to holding governments and their intelligence agencies to account. They write: "We are surprised by the recent acts by officials of your government against our colleagues at the Guardian and deeply concerned that a stout defender of democracy and free debate like the United Kingdom uses anti-terror legislation in order to legalise what amounts to harassment of both the paper and individuals associated with it."
They add: "It is deeply disturbing that the police have now announced a criminal investigation" and they warn that "the implication of these acts may have ramifications far beyond the borders of the UK, undermining the position of the free press throughout the world".
The letter's publication comes as it emerged that Scotland Yard will face legal action over its use of anti-terrorism powers to question people at airports unless it hands over the results of investigations into alleged misuse by its officers.
The Independent Police Complaints Commission has said it has given the force seven days to reveal findings into outstanding complaints about the use of the tactic following its "continued refusal" to investigate. The watchdog said it was supervising 18 investigations into the use by the Met of Schedule 7 powers, which allow officers to detain passengers for up to nine hours without needing reasonable suspicion of involvement in terrorism.