Spain has objected to an official British complaint over claims a Spanish patrol boat fired on a jetskier off the coast of Gibraltar, saying that the protest is unsubstantiated.

A spokesman from Spain's foreign office said the British chargé d'affaires in Madrid had met the ministry's political director, Ignacio Ibáñez, on Monday.

"In the meeting they had, we strenuously denied any incident had occurred in Spanish waters adjacent to Gibraltar," the spokesman said on Wednesday. "And this ministry has expressed its uneasiness to the United Kingdom over its acting on an unchecked and unfounded rumour."

The Madrid meeting follows a protest by Britain's minister for Europe, David Lidington, to his Spanish counterpart, Íñigo Méndez de Vigo, over the alleged shooting on Sunday and what the former said was an illegal incursion by a boat belonging to Spain's civil guard.

"I made clear that the discharge of a weapon in or near Gibraltar is completely unacceptable. I urged Señor Méndez de Vigo to investigate urgently and to take action to ensure that this will not happen again," Lidington said in a Foreign Office statement.

According to reports, a 32-year-old Briton called Dale Villa claims a civil guard vessel chased him when he was trying out a new jetski near the British enclave in south-west Spain, and fired at him and a passenger without warning. A 19-second video purporting to show the incident has been posted on YouTube, in which the wake from two distant vessels can be seen.

The civil guard, which is responsible for patrolling Spain's coastline, denies all knowledge of the alleged incident.

The current spat is the latest in a series of disputes over rival claims to Gibraltar dating back three centuries. Although the treaty of Utrecht forced Spain to cede control of "the Rock" to Britain in 1713, Madrid has always claimed sovereignty and civil guard vessels often enter waters off the coast of the tiny territory.

Spain formally apologised to Gibraltar in 2009 after civil guards landed on the Rock while chasing suspected smugglers.

Many Spaniards gladly commute to work in Gibraltar from the neighbouring province of Cádiz, where unemployment is almost 40%. But the peninsula has otherwise been a thorn in the side of British-Spanish relations. Last year, Spain's Queen Sofia snubbed her British counterpart's jubilee celebrations in protest against a visit to Gibraltar by Prince Edward.