The Ministry of Defence (MoD) has admitted accidentally leaking secret information on UK nuclear submarine operations.
The Government department put the leak down to a technical error, which allowed anyone to copy and paste blacked-out parts of an MoD report into another document to reveal the sensitive information.
The report was placed online following a Freedom of Information (FOI) request by anti-nuclear campaigners.
"As soon as we were aware of this incident, we took immediate steps to ensure the document was removed from the public domain and replaced by a properly redacted version," an MoD spokesperson said.
"We will check past FOI responses and review our processes for the release of sensitive information to prevent any recurrence of this type"
Information in the report covered vulnerabilities in UK submarines and expert commentary on how much of a structural failure could lead to a core meltdown onboard a nuclear sub, according to the Daily Star Sunday.
It also talked about US submarine operations when dealing with disasters, showing American vessels were twice as safe as the UK's in key areas.
The MoD has now replaced the report with an updated document to prevent any copy and pasting of secret data.
A senior MoD source told the paper it was a "hugely embarrassing" incident.
"Whoever is responsible should be sacked. The Americans will be furious their procedures have been exposed," the source added.
The Government has come under heavy fire for IT blunders in recent times.
An Institute for Government report released last month claimed the Government had wasted billions because of IT failures.
