Spain stirred up long-running diplomatic tensions on Wednesday with a statement saying it too sought "bilateral dialogue with the UK" over Gibraltar.
In its statement, the Spanish Foreign Ministry said that "like Argentina, Spain unequivocally hopes for purely bilateral dialogues with the United Kingdom to find a definitive solution to both issues affecting the territorial integrity of Argentina and Spain".
Both the UK and Gibraltar governments were swift to respond, dismissing bilateral sovereignty talks out of hand.
"Our position on the sovereignty of Gibraltar is unchanged," said a statement from the Foreign and Commonwealth Office.
"We will protect the right of the people of Gibraltar to determine their political future. The UK will never enter into arrangements under which the people of Gibraltar would pass under the sovereignty of another State against their wishes."
"Furthermore, the UK will not enter into any process of sovereignty negotiations with which Gibraltar is not content. We believe that dialogue involving the UK, Spain and Gibraltar, remains the best means to make progress towards a better relationship with Spain over Gibraltar in the long term."
The Gibraltar government reiterated that the tiny British Overseas Territory would never consent to bilateral discussions on sovereignty and called on Spain to “abandon its medieval claim".
"Her Majesty's Government of Gibraltar will never consent to the United Kingdom entering into any process of talks, discussions or negotiations with Spain in respect of the Sovereignty of Gibraltar," No 6 Convent Place said.
“We would wish to see Spain finally come into the twenty first century and abandon its medieval claim to Gibraltar and the unacceptable way in which it has recently aggressively pursued it.”
Gibraltar was ceded to the British by Spain under the 1713 Treaty of Utrecht but Spain still claims sovereignty over the territory and surrounding waters. London says it will not do so against the wishes of Gibraltarians, who are staunchly pro-British.
Tensions over Gibraltar have become increasingly fraught under the conservative government of Mariano Rajoy, which abandoned tripartite talks designed to improve relations over The Rock.
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The row reached a climax in the summer of 2013 when a spat over fishing rights resulted in Spain imposing retaliatory checks at the border, causing lengthy queues for workers and tourists crossing between Gibraltar and southern Spain.
Spain has been accused of repeated incursions into British Gibraltar Territorial Waters.