A Spanish warship entered the waters around Gibraltar and disrupted a British forces parachute training exercise, it has emerged.

Military chiefs were forced to suspend the session while the Gibraltar Squadron's patrol boat, HMS Sabre, shadowed the Spanish navy ship.

Warnings were issued to the Spanish vessel, which is said to have used a fake name and call sign, but it left only after radioing back that it was in Spanish waters, the Gibraltar Chronicle reported.

According to the newspaper, special forces personnel from the Royal Navy's Submarine Parachute Assistance Group were carrying out training jumps into the sea when the vessel approached.

Tensions over the disputed territory have been rising since the construction of an artificial reef by the Gibraltar government last year, which the Spanish said interfered with their fishing industry. Madrid responded by imposing tighter border controls, leading to long delays at the frontier for some visitors.

Repeated incursions into Gibraltar's waters by Spanish vessels followed, which led to the Spanish ambassador being publicly summoned to the Foreign Office on a number of occasions.

In November, a British diplomatic bag was opened and searched by Spanish Guardia Civil officers on the border with Gibraltar – an incident the Foreign Office described as a serious infringement of international diplomatic protocols.

A Ministry of Defence spokesman said: "The Royal Navy patrols and continues to challenge all unlawful incursions into British Gibraltar territorial waters by Spanish state vessels by issuing appropriate warnings.

"This forms an important part of her majesty's government's commitment to uphold our sovereignty against unlawful incursions with a range of proportionate naval, police and diplomatic responses.

"There should be no doubt that the MoD remains absolutely committed to ensuring the defence and security of Gibraltar, its residents and British Gibraltar territorial waters."