Staff at a shipyard in northern England that builds Britain’s nuclear submarines were evacuated after what a local news website reported was a bomb warning on a nuclear submarine.

“Following an extensive sweep of the Devonshire Dock Complex (DDC), including the four Astute class submarines in build, nothing suspicious was found,” a spokeswoman for BAE Systems told The Independent. “We expect to be able to close the incident shortly.

“Our first priority is always the safety of employees, the site and local residents so in accordance with our emergency procedures, we made the decision to release personnel from the DDC earlier today. This was purely precautionary.”

After working with the emergency services at the scene, BAE said they were ”now satisfied there is no immediate safety risk” and said employees were being asked to report to the site as normal.

Ambulances and police were on the scene in Barrow-in-Furness.

An unidentified source told The Mail, a Barrow-in-Furness-based publication, that staff had been evacuated after a warning about a bomb on an Astute-class nuclear attack submarine.

A spokesperson for Cumbria Police said: “Police are on-site at BAE assisting staff.”

A spokeswoman for the North West Ambulance Service said: “We are in attendance as a precautionary measure.” She said there had been no casualties.

“We have been made aware of an incident at the BAE Systems site in Barrow,” a spokesperson for the Office for Nuclear Regulation said. “The incident is not related to nuclear safety.

“We are liaising with BAE Systems’ site security and will continue to monitor the situation.”

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The shipyard makes the new generation of four Dreadnought-class ballistic missile submarines intended to eventually replace the Vanguard class, which forms the basis of the UK’s Trident nuclear deterrent.