The Argentinian president has criticised David Cameron for insisting the Falkland Islands should remain a British territory.
Cristina Kirchner described the prime minister as "arrogant" and said his comments were an "expression of mediocrity and almost of stupidity".
Cameron had been prompted by Conservative MP Andrew Rosindell during prime minister's questions to remind Barack Obama that the British government would not accept any kind of negotiations over the south Atlantic islands, over which Argentina and Britain fought a 10-week war in 1982.
Cameron told the Commons: "I would say this: as long as the Falkland Islands want to be sovereign British territory, they should remain sovereign British territory – full stop, end of story."
In her criticism of his comments, Kirchner said Britain "continues to be a crude colonial power in decline".
She has insisted the two countries should negotiate over the islands, which have been a British territory since 1833. The 1982 conflict, which cost the lives of 649 Argentinian and 255 British troops, ended when the invading Argentinian forces surrendered on 14 June, now celebrated by the islanders as liberation day.
On Wednesday the commander of the naval task force that recaptured the Falklands warned they had since become "perilously close to being indefensible" against an Argentinian attack.
Writing in the Daily Mail, Admiral Sandy Woodward cited the lack of an aircraft carrier and weakening US support for British sovereignty. "The simple truth is without aircraft carriers and without the Americans we would not have any hope of doing the same again today." Last year, five retired commanders warned that the scrapping of the Harrier jets and HMS Ark Royal as part of defence cuts amounted to an invitation to invade the Falklands.
The Ministry of Defence has dismissed Woodward's articles as "completely without substance".
This week a British man became the first Falkland islander to choose Argentinian citizenship. On the 29th anniversary of the end of the war, James Peck, whose father was killed fighting on the British side during the conflict, was presented with an identity card by Kirchner.
