The detention of a Guardian journalist's partner by police at Heathrow airport appears to be a "clear abuse" of counter-terrorism laws, according to a backbench Lib Dem.
Cambridge MP Julian Huppert, the Lib Dem member of the Commons home affairs committee, said the holding of Glenn Greenwald's partner David Miranda would form part of the committee's inquiry into the UK's anti-terrorism legislation.
"The Miranda case seems a clear abuse of the over-broad terrorism laws. We've tightened them a bit - but clearly far more needs doing," he said on Twitter.
And Huppert told The Huffington Post UK that the incident "raises questions about what the home secretary's and prime minister's involvement was".
A Downing Street source told the Press Association on Tuesday that No. 10 was "kept abreast of the operation in the usual way" but denied any political involvement in the decision to detain Miranda.
Yesterday White House spokesman Josh Earnest said the British government gave the United States advance notice that London police intended to detain Miranda but added that the US did not request the detention and was not involved in the decision.
Miranda was detained under the controversial Schedule 7 of the Terrorism Act 2000 which - passed by the previous Labour government.
The coalition has already said it intends to limit the powers available to police under the law, but Huppert said the government would "need to be looked at again now it is clear how broad this legislation is".
"I am very alarmed about it, it does seem to be an abuse," he said. "Hassling people around journalists, that is clearly nothing we want to see."
He added: "There is also a need for proper guidance as to what counts as a genuine terrorist thereat."
Huppert also said that while it was "astonishing" that Miranda had been detained, at least he had the support of The Guardian.
"There are thousands and thousands of people who are stopped under Schedule 7 and most don't have anything like the same level of support," he said. "The effect it is having on the Muslim community is really quite powerful."
The Lib Dem said the home affairs committee would examine how Miranda was treated as part of its ongoing investigation into anti-terror legislation. "Clearly this will now have to form part of the inquiry, it ill be very, very timely," he said.
Scotland Yard has defended the detention as "legally and procedurally sound". And the Home Office has said "the government and the police have a duty to protect the public and our national security".
Miranda said he was questioned by six agents on his "entire life" while being held at Heathrow for nine hours - the legal limit before a suspect must be charged or released.
Greenwald - the reporter who interviewed American whistle-blower Edward Snowden - called Miranda's detention a "profound attack on press freedoms and the news-gathering process".
"To detain my partner for a full nine hours while denying him a lawyer, and then seize large amounts of his possessions, is clearly intended to send a message of intimidation to those of us who have been reporting on the NSA (US National Security Agency) and GCHQ," he said.
On Tuesday the editor of The Guardian, Alan Rusbridger, revealed British intelligence officials smashed hard drives in the basement of the newspaper's London headquarters.
He claimed agents threatened the paper with legal action over the Edward Snowden intelligence leaks and told him: "You've had your fun, now we want the stuff back."
Miranda was stopped at 8.30am on Sunday when returning from a trip to Berlin. He was questioned under schedule 7 of the Terrorism Act 2000 which applies only at airports, ports and border areas, allowing officers to stop, search, question and detain individuals.