William Hague has accused Argentina of "bullying and intimidatory" behaviour over the Falklands as he insisted the islands would remain British for centuries.
The Foreign Secretary dismissed claims from Argentinian counterpart Hector Timerman that the Falkland Islands would be controlled from Buenos Aires within 20 years.
Mr Hague said the suggestion was a "fantasy" and said the tactics adopted by Argentina were counterproductive.
On a visit to London last week Mr Timerman refused to attend a meeting with the Foreign Secretary because representatives of the islanders were present.
Mr Timerman told reporters at the Argentine ambassador's residence that as far as Buenos Aires was concerned, Falkland islanders do "not exist".
But Mr Hague told The Sun: "This is a community that is nearly 200 years old. They seem very determined to remain British.
"If there's any chance they would change their minds, the approach by Argentina is completely counterproductive.
"It only fortifies the islanders' determination to stay British. It is only going to add to the decades and centuries that the Falklands will remain British."
The islanders will vote in a referendum next month which is expected to underline their determination to remain a British overseas territory.
Mr Hague said the current Argentine government, led by president Cristina Fernandez de Kirchner had turned away from a process of diplomatic dialogue "into a pattern of bullying and intimidatory behaviour towards the Falkland Islands".