A picture taken on July 20, 2016 in the port of Gibraltar shows the nuclear submarine HMS Ambush (C) making an unscheduled stop in Gibraltar due to a sustained damage to its conning tower after a "glancing collision" with a merchant vessel.
PHOTO: DM PARODY/AFP/AFP/Getty Images
A picture taken on July 20, 2016 in the port of Gibraltar shows the nuclear submarine HMS Ambush (C) making an unscheduled stop in Gibraltar due to a sustained damage to its conning tower after a "glancing collision" with a merchant vessel.
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Story highlights

The incident occurred during a training exercise

The nuclear plant on the submarine was not affected

(CNN) —  

A nuclear submarine was damaged Wednesday after it was involved in a “glancing collision” with a merchant vessel, the UK Ministry of Defense said in a statement.

The sub suffered external damage, but “there is absolutely no damage to her nuclear plant,” authorities said. No one was injured and the merchant vessel was not damaged, according to initial reports.

The collision between HMS Ambush, an Astute-class submarine, and the other ship happened while the submarine was submerged and conducting a training exercise.

The incident occurred at around 1:30 p.m. local time off the coast of Gibraltar.

An investigation is underway, and the submarine is set to return to Gibraltar to be checked.

The Astute-class submarines are described as the “largest, most advanced and most powerful attack submarines ever operated by the Royal Navy.”

The HMS Ambush was commissioned in March 2013, according to the Royal Navy. It’s one of three Astute-class subs in the Royal Navy that are currently active.

CNN’s Milena Veselinovic contributed to this report