The president of Argentina, Cristina Fernandez de Kirchner, has called Britain "arrogant" for refusing to negotiate on the Falklands.
She was speaking a day after UK Prime Minister David Cameron said the issue of sovereignty was non-negotiable.
President Fernandez called his refusal to hold talks on the sovereignty of the Falklands, or Malvinas, arrogant and bordering on stupidity.
Britain defeated an Argentine invasion of the islands in 1982.
The Falklands are at the centre of a territorial dispute dating back to the 19th Century.
Argentina has repeatedly requested talks on the islands' future sovereignty.
But most Falkland islanders wish to retain British sovereignty and 14 June is marked as Liberation Day in the capital, Port Stanley.
Last week Washington called on Britain and Argentina to negotiate over the Falklands' sovereignty.
But during Wednesday's Prime Minister's Questions Conservative MP Andrew Rosindell urged Mr Cameron to remind President Barack Obama that "the British government will never accept any kind of negotiations over the South Atlantic archipelago".
Mr Cameron responded that "as long as the Falkland Islands want to be sovereign British territory, they should remain sovereign British territory - full stop, end of story."
'Crude colonial power'
President Fernandez described his comments as an "expression of mediocrity, and almost of stupidity".
She said the British "continue to be a crude colonial power in decline".
On Friday, a spokeswoman for Downing Street said the prime minister maintained his position. She said the government had made it clear to Argentina that it was prepared to hold talks but would not negotiate on sovereignty.
"We're not prepared to discuss the sovereignty of the Falkland Islands against the wishes of the Falkland people."
Earlier this week a British man became the first Falkland islander to choose Argentine citizenship.
James Peck was handed his national identity card by President Fernandez, during a ceremony to mark the 29th anniversary of the end of the Falklands War.
Mr Peck's father Terry, who died in 2006, had been a member of the Falkland Islands Defence Force.
Sir Sandy Woodward, the retired admiral who led the British taskforce which set sail for the Falklands in 1982, told a newspaper earlier this week he feared the islands were "now perilously close to being indefensible".
He told the Daily Mail: "Twenty-nine years ago today, we re-claimed the Falklands for Britain in one of the most remarkable campaigns since the Second World War.
"The simple truth is without aircraft carriers and without the Americans, we would not have any hope of doing the same again today."
Adm Woodward questioned whether the US would continue to support Britain's sovereignty over the islands, pointing to Washington's call last week for negotiations.
The Americans' reference to the islands by their Argentinian name - the Malvinas - didn't "leave too much doubt about which way the wind may be blowing", he said.