Scotland Yard has been taken to court over how it handles complaints regarding its use of controversial counter-terrorism powers.
The Independent Police Complaints Commission (IPCC) said it filed papers at the High Court yesterday after the Metropolitan Police refused to reveal the results of investigations into its use of Schedule 7 of the Terrorism Act.
Legal action calling for a judicial review was taken in "direct response" to complaints by community groups that innocent Muslims have been targeted , the IPCC said.
Schedule 7 gives officers the power to stop, question and detain people at ports of entry and departure, such as airports, even if wrongdoing is not suspected.
It received renewed scrutiny after officers used the powers at Heathrow in August to detain David Miranda, the partner of Guardian journalist Glenn Greenwald, who broke the Edward Snowden state surveillance story.
An IPCC spokesman said: "The IPCC is challenging the MPS's handling of these complaints, including its delay in investigating, its failure to investigate the reasons for stops and its failure to provide reports and background documents to the IPCC.
"The Metropolitan Police's repeated delay and reluctance to comply has left us with no option but to take this matter to the High Court to resolve the position once and for all.
"It's wholly unsatisfactory that the IPCC is denied answers to the questions complainants raise about the Metropolitan Police's use of this power and that the IPCC is prevented from carrying out its statutory role.
"This is not a problem the IPCC has encountered with any other police force and we await the High Court's determination on this matter."
Muslim community groups first raised concerns about the alleged misuse of schedule 7 in June 2011.
In August this year, the Met refused to provide the IPCC with the findings of its investigations.
After receiving a letter threatening legal action, the country's largest police force provided what the IPCC described as "incomplete reports" that did not satisfy its obligations.
Muslim passengers stopped under Schedule 7 were asked whether they carried the Koran, about their beards, and their opinions on the Queen and Barack Obama, according to reports.
One was held for hours, missed his flight, and then was stopped again as he tried to board another plane after spending the night at the terminal, The Independent reported.
Asif Bhayat, 31, told the newspaper that he had been stopped on all of the three occasions that he flew out of the country in 2012. He said that he was stopped by police on his return from a charity trip to Sarajevo, Bosnia and Herzegovina.
"I asked if it was because of the way I looked; he smiled and shrugged his shoulders," Mr Bhayat said.
The Government's reviewer of terrorism legislation is currently investigating the detention of Mr Greenwald's partner, David Miranda.
David Anderson QC said he wanted to "get to the bottom" of what had happened and asked Scotland Yard and the Home Office for a full briefing.
In a review published in July, Mr Anderson said he had found that 61,145 people had been stopped under Schedule 7 over the last year.
But claimed there was no evidence to suggest "persons of Asian appearance" were more likely to be examined.
Scotland Yard said it "recognises" the IPCC's role in scrutinising public complaints relating to Schedule 7.
A spokesman said: "We have been working hard to provide a range of options to agree a procedure for dealing with such investigations that is acceptable to all stakeholders.
"We clearly set out our position to the IPCC and have offered to provide as much information about the investigations as we can in the circumstances.
"However, despite our efforts to reach an agreement with the IPCC over the last few months, they have now served us with proceedings for a judicial review. We will now be considering the claim and will file our defence accordingly."