Spain complained about the British military presence in Gibraltar and then the next day, refuelled a Russian warship in its own overseas territory of Ceuta.

Spanish ambassador Santos said at a UN meeting on decolonisation that Spain sought the return of Gibraltar and the “illegally occupied” isthmus. Mr Santos said that since 1963, Gibraltar had been included on the UN list of territories subject to decolonisation.

“And there it remains, which demonstrates beyond doubt that the relationship between Gibraltar and the United Kingdom is colonial in nature,” he said.

“Additionally, and though it might seem obvious to mention it, I have to note that in both cases, military installations lie at the heart of the matter”, he added.

Meanwhile, across the Mediterranean at the Spanish colony of Ceuta, a Russian Navy warship is being refuelled.

Ceuta is one of two Spanish exclaves in North Africa (the other one being Melilla). The territory had several rulers before the Portuguese in 1415 took control of this city east of Tangier. Since 1580 it has been under Spanish administration but has the status of an autonomous city despite being located on the African continent almost directly south of of Gibraltar.

This has happened before, last year the Russian cruiser Marshal Ustinov was refuelled in Spain after operations in Syria, despite fresh sanctions against Russia.

The American government, backed by statements from NATO officials, had announced additional sanctions against Russia over its ongoing occupation of Crimea and its interference in eastern Ukraine.

Spain is frequently under pressure from NATO allies not to allow the refuelling of the Russian warships but does so anyway.