RADIOACTIVE water "leaked into a loch" from a nuclear weapons base after old pipes repeatedly burst, official files have revealed.
A joint investigation from The Guardian and The Ferret – also reported by the BBC – found that the material was released into Loch Long in Argyll and Bute.
It comes after a six-year battle to access documents which involved Scotland's information commissioner.
The investigation revealed that files compiled by the Scottish Environment Protection Agency (Sepa) – the environment watchdog – stated the Royal Navy failed to properly maintain a network of 1500 pipes at the Coulport armaments depot.
Coulport holds the Royal Navy's supply of nuclear warheads for its fleet of Trident submarines, which are based at HMNB Clyde at Faslane, near Helensburgh.
Sepa said the issues at Coulport, which date back to a pipe burst in 2010, were caused by "shortfalls in maintenance".
One incident listed in the files, which took place in August 2019, resulted in the release of "unnecessary radioactive waste" in the form of low levels of tritium, which is used in nuclear warheads.
The environment watchdog insisted that its assessments found the risk to the environment from effluent discharges was "of no regulatory concern".
Meanwhile, the Ministry of Defence (MoD) said there had been "no unsafe releases of radioactive material" into the environment.
The files were released after a ruling by Scottish information commissioner David Hamilton, who oversees the country's freedom of information laws.
According to The Guardian and The Ferret, the UK Government allegedly insisted the files had to be kept secret for national security reasons.
However, in June Hamilton ruled that most of the files had to be released as their disclosure did not threaten national security but "reputations".
The release of the files was delayed yet again in July by another intervention from the MoD, which cited "additional national security concerns".
The files were eventually released by Sepa on August 5.
Speaking to The Ferret, the Scottish Greens said the findings of the joint investigation were "deeply concerning" and called for "full transparency and accountability" from the MoD.
A spokesperson for Sepa said it recognised the public interest in the naval base and was committed to ensuring that it operate "in accordance with standards equivalent to those in environmental regulations".
All discharges from HMNB Clyde, Sepa's monitoring data, and an assessment of potential environmental and public impacts are published annually in the Radioactivity in Food and the Environment (RIFE) report.
"Based on these assessments the risk to the environment from effluent discharges is of no regulatory concern."
They added an "extensive replacement programme for components" had already been undertaken and the agency was satisfied that the site had made "substantial improvements" to asset management and maintenance across both Faslane and Coulport.
A MoD spokesperson said: "We place the upmost importance on our responsibilities for handling radioactive substances safely and securely.
"There have been no unsafe releases of radioactive material into the environment at any stage.
"We frequently engage with regulators who report there is no significant impact on the environment or public health and are supportive of an open reporting culture."
