The director of public prosecutions will not allow a private prosecution of terror suspects Babar Ahmad and Syed Ahsan, because no real evidence has been provided and any case against the men would be "bound to fail" in a British court.
The private prosecution was launched by a British businessman Karl Watkin, who campaigns against Britain's extradition agreement with the US.
But Keir Starmer QC said the documents provided by British businessman Karl Watkin were "very short, lack any meaningful detail and do not provide any real support for a prosecution".
Mr Watkin made the attempt to bring legal proceedings against the pair in the UK to avoid "outsourcing the country's criminal justice system" to the US.
Mr Starmer said the DPP was not provided with enough evidence to prosecute Mr Ahmad, as the attempt relied on "two statements and a number of documents".
"The two statements purport to have been signed by Mr Ahmad and Mr Ahsan themselves but they are very short, lack any meaningful detail and do not provide any real support for a prosecution," he said.
"Most of the documents provided appear to have been printed off from websites.
"As they stand, they are probably inadmissible in evidence but, in any event, they do not provide the necessary links between Mr Ahmad and Mr Ahsan and the charges that Mr Watkin proposes to bring under the Terrorism Act 2000.
"Any prosecution on such material alone would be bound to fail."
Mr Starmer added that the Metropolitan Police only submitted "a small number of documents" relating to Mr Ahmad in 2004 and does not intend to refer any further material to the Crown Prosecution Service for consideration.
And any suggestion that material provided by the United States could be used in support of a prosecution in England and Wales is "misconceived", he said.
"That material was provided in accordance with the requirements of the Extradition Act 2003 solely for use in the extradition proceedings, which relate to the wider charges alleged in that jurisdiction."
Mr Watkin told Channel 4 he had spent £250,000 of his own money fighting the extradition treaty, with he and others having budgeted £150,000 for the Ahmad case and spent £20,000 so far.
"For me it is about the extradition treaty. I am opposed to the treaty 100 per cent. It should be torn up because it is completely one-sided," he said.
"British people should be subject to British law. I am an international businessman and I always stand up for the rights of people who are getting abused."
Mr Ahmad has been in jail without trial since 2004 while fighting extradition and has pleaded to be charged and tried in Britain.
The pair are accused of being involved in a website which encouraged terrorism and which, while operated from London, was hosted in the US.
On Monday morning, Ahmad launched a High Court bid to halt his removal from the UK, after the European Court of Human Rights ruled last month that Ahmad, along with the notorious Abu Hamza and four other terror suspects, refused to halt their extradition.
A panel of five judges threw out their request to the Grand Chamber of the European Court of Human Rights.
The computer expert's judicial review application is now expected to be heard tomorrow along with that of radical cleric Abu Hamza and another suspect, Khaled Al-Fawwaz.
The last-ditch challenges will be heard by two judges in London - Sir John Thomas, President of the Queen's Bench Division, and Mr Justice Ouseley,
Ahmad has been held in a UK prison without trial for eight years after being accused of raising funds for terrorism.