The Home Secretary, Jacqui Smith, is to be questioned by MPs over whether Britain's fight against terrorism has been compromised after a second security breach involving secret documents being left on a train.
The second blunder, revealed in The Independent on Sunday, is deeply embarrassing for the Government and has led to calls for all civil servants to be stopped from taking documents home until the Whitehall regime is tightened. Sir Gus O'Donnell, the cabinet secretary, is writing to all permanent secretaries reminding them of the existing rules over the handling of sensitive documents.
The first breach occurred when top secret documents, including a Home Office report on "al-Qa'ida vulnerabilities", were left on a train last week and handed to the BBC.
An intelligence officer working at the Cabinet Office was suspended pending a full investigation after leaving the seven pages of files on a commuter train. Marked "UK Top Secret", the intelligence assessment on al-Qa'ida is so sensitive that every document is numbered and marked "for UK/US/Canadian and Australian eyes only".
Yesterday it was revealed that a second batch of documents had been left on a train to Waterloo. These were passed to The Independent on Sunday. The confidential files included briefing notes for a meeting today organised by the Financial Action Trust Force (FATF), an inter-governmental body created to combat financial crime and the funding of terrorism.
Keith Vaz, the Labour chairman of the Commons Home Affairs Committee, said he would question the Home Secretary at a hearing tomorrow on whether the latest losses of secret papers are hampering the fight against terrorism.
"There is a simple solution to this – that is people should just not take these documents out of departments if they are confidential ... until various inquiries are completed," he said.
"Only on Thursday, the Government told Parliament that it had established an inquiry into the confidential documents left by an official on a train and handed to the BBC. This latest revelation gives us serious cause for concern," Mr Vaz said.
"We need an explanation from the Home Secretary whether all these breaches of security affect our fight against terrorism.
"Until the inquiry has been concluded and we are told how these extraordinary events occurred, no official, no matter how senior, should be allowed to take classified or confidential documents outside their offices for whatever reason."
Dominic Grieve, the new shadow Home Secretary, accused the Government of being "shambolic".
The frequency with which data was being mislaid or lost by the Government, including data discs containing the details of 25 million people, gave grave cause for concern, he said.
"This is a Government that spends a lot of time on presentational politics and is not very good at basic administration," he said. "It is shambolic."
The Independent on Sunday did not divulge the contents of the second batch of documents and returned them to the Government. The files include draft speeches to be delivered today by Government officials at No 11 Downing Street at a reception for the FATF leaders on Wednesday.
The latest lapse has raised concerns among Britain's allies about its ability to ensure the safety of information it is passed.
The Foreign Secretary, David Miliband, told the BBC: "The Government takes all reports of security breaches extremely seriously. These sorts of lapses are completely inexcusable.
"I know that this will be taken with the utmost seriousness and will be followed up to ensure that there isn't a further threat to the national interest."
Geoff Hoon, Labour's Chief Whip, said the Government was taking the loss of the documents "extraordinarily seriously". He told Sky News that a full investigation would follow but that a lot of the information contained in the files had already been made public.
"There will be a thorough investigation, but can I emphasise that, as I understand it, much of this material was actually already in the public domain and therefore is not classified.
"But that is not to say that we will not look at this extremely seriously."