A UK nuclear submarine, HMS Sceptre, has docked in Gibraltar for repairs, prompting protests from Spain.
HMS Sceptre is expected to stay in dock for six days
Spanish Foreign Minister Miguel Angel Moratinos said he had asked the UK that no more nuclear submarines be sent to the Rock for maintenance work.
Visits by UK submarines have been a cause of concern for Spain - especially since HMS Tireless needed repairs to a pipe near its nuclear reactor in 2000.
Madrid wants the Rock returned to Spain but Gibraltarians want to stay British.
Last year marked 300 years of UK rule of the Rock.
HMS Sceptre arrived in Gibraltar, at the southern tip of Spain, on Thursday.
Mr Moratinos told Spanish television the visit could not be compared to the almost year-long stay by HMS Tireless, when there were fears the damage could cause a leak and contaminate the environment.
"The breakdown is purely in the diesel engine's cooling systems," he said.
"That is to say - and I wish to clarify this - it is not in the submarine's nuclear system.
"We have asked that no more nuclear submarines be given repairs for this kind of breakdown in future, whatever their nature or scale, and for us in future to be able to restore calm in our co-operation with the United Kingdom, which we want to be as fruitful as possible."
A UK Ministry of Defence spokesman said HMS Sceptre had been scheduled to stop in Gibraltar and was taking the opportunity to carry out repairs on its water cooling system in the diesel room.
"There is no question of any nuclear repairs or nuclear safety issues," he told the BBC News website.
The UK Foreign Office refused to comment on the contents of the conversation between Mr Moratinos and Foreign Secretary Jack Straw.
The submarine is due to leave Gibraltar on 9 February.