Documents released by the American whistle-blower Edward Snowden claim that Britain spied for several years on the Argentine government.
According to reports in the Argentine media, Britain was concerned that Argentina could launch another attempt to reclaim the Falkland Islands.
The two nations fought a war over the islands in 1982.
Last month the British government announced it was upgrading its military presence on the islands.
Mr Snowden says British agents were actively spying on Argentina between 2006 and 2011.
The former CIA worker, who now lives in Russia, has previously leaked sensitive information about US surveillance programmes.
The BBC’s South America correspondent Wyre Davies says there has not been any formal response yet from either the British or Argentine government to the allegations, which have been published by a number of Argentine news agencies.
The claims are that Britain began a large scale operation which may have involved implanting computer viruses, circulating false propaganda and collecting intelligence with the aim of diminishing or discrediting the Argentine government, our correspondent added.
The news comes around the 33rd anniversary of the start of the war, which saw more than 900 servicemen killed.
Defence Secretary Michael Fallon said last month that Britain will spend £280m over the next 10 years on renewing and beefing up its defences of the Falkland Islands, to taking into account “any future and possible threats” to the islands.
Meanwhile, Argentine foreign ministry officials say they will prosecute oil companies operating near the Falkland Islands, which are known as Las Malvinas in South America.
The officials said companies active there were operating illegally in Argentine territory.
Earlier this week, three British oil exploration companies announced new oil and gas finds north of the islands.
And Argentine President Cristina Fernandez said Britain should spend more helping its own poor than on defending the Falkland Islands.
Delivering a speech to honour her country’s war dead in the conflict, she said: “What a paradox when there are more than one million Britons eating at the food banks they have had to open in one of the most powerful countries in the world.
“Don’t worry. Don’t spend another pound sterling on defending the Malvinas.
“Spend your money feeding the English, on providing jobs for your young people and a better quality of life for the British, because we are not a threat to anyone.”
She has also ordered the declassification of all her country’s secret documents on the war.
Guide to the islands:
- The Falkland Islands are an isolated and sparsely populated British overseas territory in the south-west Atlantic Ocean
- They remain the subject of a sovereignty dispute between Britain and Argentina, who waged a brief but bitter war over the territory in 1982
- Argentine forces landed on the Falklands on 2 April 1982 to stake a territorial claim, but by 14 June they had been ejected by a British military task force
- The fighting cost the lives of 655 Argentine and 255 British servicemen
- Argentina says it has a right to the islands, which it calls the Malvinas, because it inherited them from the Spanish crown in the early 1800s
- It has also based its claim on the islands’ proximity to the South American mainland
- Britain rests its case on its long-term administration of the Falklands and on the principle of self-determination for the islanders, who are almost all of British descent.