Spain is seeking an urgent explanation from British authorities after a Royal Navy submarine was forced into port in Gibraltar following a collision with a merchant vessel.

In a statement Thursday, the Foreign Ministry said the government was seeking all information from the British embassy in Madrid regarding the damage done to the submarine and how the prior day's incident occurred.

The British Royal Navy said HMS Ambush's nuclear reactor was not damaged in the incident when the Astute-class submarine became "involved in a glancing collision with a merchant vessel" while submerged and conducting a training exercise.

It added that the vessel suffered some external damage but that no crewmembers were hurt.

Photographs of the submarine show its conning tower damaged.

The navy said it was in contact with the merchant vessel "and initial indications are that it has not sustained damage."

The Astute-class vessels carry torpedoes for targeting enemy submarines and ships and Tomahawk cruise missiles.

The Spanish ministry said the government had been aware the submarine was in the area.

Spain has expressed its annoyance over the presence of British nuclear submarines in Gibraltar in the past.

Spain ceded sovereignty of Gibraltar to Britain in 1713, but has persistently sought its return.

Gibraltar's 30,000 residents are firmly in favor of remaining British.