Argentina's ambassador to the UK has denied insulting David Cameron in a fresh spat between the countries over the sovereignty of the Falkland Islands.

Alicia Castro appeared to mock the Prime Minister in remarks at the senate in Buenos Aires, saying he was "silly" to have raised the views of Pope Francis about the disputed territory.

When the former bishop of the Argentine capital was named the new pontiff in March, Mr Cameron publicly said he disagreed with his view that the UK had "usurped" the islands.

He also drew on Vatican tradition to joke about the clear backing in a referendum of islanders for remaining a UK overseas territory, saying the "white smoke over the Falklands was pretty clear".

At a meeting of the Senate's foreign affairs commission, the ambassador is reported to have dubbed the Prime Minister stupid and dumb and called his criticism of the Pope's stance "inefficient".

"Cameron was so stupid and inefficient when Pope Francis was chosen as the new papal leader because he broadcast what he had been saying about the Malvinas," she is reported to have said, using the Spanish name for the Falklands.

It swiftly drew calls from British MPs for an apology from the diplomat. As UK officials sought clarification, the Argentine embassy insisted the comments were "taken out of context".

"With her comments Ambassador Castro referred exclusively to the failure of a communication strategy," it said.

"They were not meant as an affront to Mr Cameron, nor to the Prime Minister's office."