The Commons home affairs committee has summoned the Metropolitan police to explain its failed attempt to use the Official Secrets Act against the Guardian.
Earlier in the week the Met attempted to force Guardian reporters to reveal their sources for articles relating to the phone hacking of murdered schoolgirl Milly Dowler.
The move is sure to cause acute embarrassment for the Met, early in the tenure of new commissioner Bernard Hogan-Howe.
Keith Vaz, chair of the home affairs committee, said: "I have asked the Metropolitan police to give the committee a full explanation of why they took the decision to invoke the Official Secrets Act and to provide us with a timeline as to exactly who was consulted.
"I am also concerned to find out what action the Metropolitan Police have taken to prevent further information leaks from Operation Weeting. It is essential that we get the full facts."
Mark Simmons, deputy assistant commissioner, will provide a private briefing to the committee this Friday, on the same day that officers had intended to take the Guardian to court.
The Met has already suffered a humiliating climb-down on the issue amid a storm of criticism from MPs, newspapers and online commentators.
Scotland Yard said in a statement yesterday: "The Met has taken further legal advice this afternoon and as a result has decided not to pursue, at this time, the application for production orders."
"This decision does not mean that the investigation has been concluded.
"Despite recent media reports there was no intention to target journalists or disregard journalists' obligations to protect their sources.
"It is not acceptable for police officers to leak information about any investigation, let alone one as sensitive and high profile as Operation Weeting."
The consent of the director of public prosecutions is needed before most prosecutions under the Official Secrets Act, suggesting he strongly discouraged the Met from its course of action.
The deputy assistant commissioner of the Metropolitan police told the Guardian today the use of the Act was "not appropriate".