The former Guantanamo Bay detainee Moazzam Begg has had seven terror charges against him dropped by the Crown Prosecution Service.
The charges were all connected to the conflict in Syria and included an allegation that he attended a terrorist training camp there.
Mr Begg is expected to be released from Belmarsh Prison in south London later on Wednesday.
He was arrested along with three others in February this year.
The prosecution said there was insufficient evidence to bring him to trial on terrorism charges.
An Old Bailey judge entered a formal verdict of not guilty on Wednesday and ordered that Begg be set free immediately from Belmarsh high security prison.
The 45-year-old from Birmingham had spent seven months in custody after being arrested and questioned over a trip he had made to Syria.
He was facing seven charges of possessing a document for the purposes of terrorism funding and training, and attending a terrorism training camp.
At a hearing five days before his trial was due to begin, Christopher Hehir prosecuting, said: “The prosecution have recently become aware of relevant material, in the light if which, after careful and anxious consideration, the conclusion has been reached that there is no longer a realistic prospect of conviction in this case.
“The prosecution therefore offers no evidence.”
Begg’s lawyer, Gareth Peirce, said he should never have been charged, as his activities did not amount to terrorism.
“This is a good man trying to the right thing in a very difficult world,” he said.
Meanwhile, Begg’s workplace CAGE issued a statement welcoming his release.
“CAGE is delighted to announce that all seven charges against our Outreach Director Moazzam Begg have now been dropped by the Crown Prosecution Service due to lack of evidence.
“This is the second time that a major Western country has held Moazzam Begg without trial and so serious questions must be asked about why this has been allowed to happen for a second time. CAGE calls for those responsible for his needless incarceration to be held to account.
“We thank everyone for their support in what has been a testing time for Moazzam, his family and the rest of the CAGE family.”
Crown Prosecution Service
There was no immediate explanation from the Crown Prosecution Service about the material that it said had recently come to light.
Begg had denied attending a terrorist training camp in Syria “knowing or believing instruction or training was provided there for the purposes of terrorism” between 9 October 2012 and 9 April 2013.
He had also denied five charges of possessing articles for purposes connected with terrorism between 31 December 2012 and 26 February 2014.
The counts related to electronic documents found on a laptop computer in his possession.
Begg had further denied being involved in a funding arrangement between 14 July 2013 and 26 February 2014 by making available a Honda generator.
Begg was previously arrested in February 2002 in Pakistan, spending three years detained without charge at Bagram prison north of Kabul and then Guantánamo Bay.
He was eventually released on 25 January 2005.
West Midlands police refused to make public the new material that the CPS said had come to light.
Ast Ch Con Marcus Beale said: “New material has recently been disclosed to police and CPS, which has a significant impact on key pieces of evidence that underpinned the prosecution’s case. Our criminal justice system – quite rightly – demands a very high standard of proof.
“I understand this is going to raise many questions. However, explaining what this newly revealed information is would mean discussing other aspects of the case which would be unfair and inappropriate as they are no longer going to be tested in court.
“From the beginning this case has challenged the relationship between West Midlands police and some of the communities we serve. I would like to reassure them and Mr Begg that at every stage of this investigation my officers acted in the best interests of the public and of justice.”