A secretive British police investigation focusing on journalists working with Edward Snowden’s leaked documents remains ongoing two years after it was quietly launched, The Intercept can reveal.

London’s Metropolitan Police Service has admitted it is still carrying out the probe, which is being led by its counterterrorism department, after previously refusing to confirm or deny its existence on the grounds that doing so could be “detrimental to national security.”

The disclosure was made by police in a letter sent to this reporter Tuesday, concluding a seven-month freedom of information battle that saw the London force repeatedly attempt to withhold basic details about the status of the case. It reversed its position this week only after an intervention from the Information Commissioner’s Office, the public body that enforces the U.K.’s freedom of information laws.

Following Snowden’s disclosures from the National Security Agency in 2013, the Metropolitan Police and a lawyer for the British government separately stated that a criminal investigation had been opened into the leaks. One of the London force’s most senior officers acknowledged during a parliamentary hearing that the investigation was looking at whether reporters at The Guardian had committed criminal offenses for their role in revealing secret surveillance operations exposed in the Snowden documents.

In January, The Intercept sought details about the status of the investigation through requests made under the Freedom of Information Act. But the Metropolitan Police, the largest and most powerful of the 45 regional police forces across the United Kingdom, stonewalled the requests. It cited fears about “increased threat of terrorist activity” and claimed that it could not reveal details about the investigation because they could “assist any group or persons who wish to cause harm to the people of the nation.”

In March, The Intercept filed a formal complaint with the Information Commissioners Office over the police force’s refusals, and the oversight body met with police officials to discuss their handling of the case. After months of delays, the force stated in an emailed letter Tuesday that it “can confirm that it continues to conduct an investigation” related to the leaked documents and the people who have handled them. However, it declined to provide any information about the amount of taxpayers’ money spent on the probe or disclose the number of officers working on it, insisting that it does not hold records of these details.

The admission that the investigation remains ongoing triggered criticism from the U.K.’s largest journalists’ organization. Michelle Stanistreet, general secretary of the National Union of Journalists, called on the police to “stop attacking press freedom.”

“Journalists who reported on the Snowden documents are not criminals, they are not a threat to national security,” Stanistreet said in a statement issued to The Intercept. “It is totally unacceptable that the authorities have spent the last two years considering whether they will prosecute British journalists reporting in the public interest.”

Snowden’s first disclosures from the NSA were published in June 2013 by Glenn Greenwald in The Guardian. Greenwald, who was then a columnist for the London-based newspaper, left in October 2013 to co-found The Intercept. The Guardian’s revelations included details about dragnet U.K. Internet spying operations, the exposure of which infuriated top British government officials and led to the newspaper being pressured into destroying hard drives containing copies of the documents.

“They are trying to shake down and instill fear into journalists.”

In Aug. 2013, at the pinnacle of the British backlash, Greenwald’s partner David Miranda was detained and interrogated for nine hours as he was passing through a London airport, and an encrypted set of Snowden files he was carrying to aid Greenwald’s reporting was seized.

Four days later, the Metropolitan Police quietly announced that its Counter Terrorism Command had opened a criminal investigation related to the leaks, saying the documents were “highly sensitive” and could “put lives at risk” if published. A London counterterrorism detective stated in a court hearing about the case that it was being viewed as a “conspiracy with a global dimension.”

Despite these assertions, however, the police are yet to charge anyone with an offense in relation to the Snowden debacle.

Media lawyer Mark Stephens told The Intercept he believes there is little realistic prospect of a prosecution being brought against any journalists — and said he thinks the authorities are more interested in creating a “chilling effect” to stifle reporting on secretive national security-related issues.

“The main reason the investigation is still carrying on is probably to create a degree of uncertainty around journalists and their advisers about what can and cannot be done in terms of carrying documents,” said Stephens, who is a partner at London firm Howard Kennedy. “They are trying to shake down and instill fear into journalists and discourage them from exposing things that have to do with national security.”

According to Stephens, the police would need to have a high degree of confidence that the prosecution would be successful to move it forward, and they would also have to show that prosecuting journalists served the public interest, which would be difficult.

The Metropolitan Police had not responded to requests for comment on this story at time of publication.