Argentina's government has begun a determined campaign to deter British-based energy companies from drilling for oil in disputed waters around the Falkland Islands in the south Atlantic.
On the eve of a visit by UK parliamentarians to Buenos Aires next week, the Argentine embassy in London on Thursday warned that legal action was being ramped up against drillers and their suppliers.
More than 200 letters have already been sent to oil companies, City analysts and the London Stock Exchange, explaining that Argentina considers that companies such as Premier and Rockhopper are operating in a clandestine way.
Embassy sources said access to the "highly promising" shale gas and other deposits onshore, and offshore around Argentina, would be denied to any company drilling off the Falklands, known locally as the Malvinas.
"It is a political issue. If you find that shale in Argentina is good business then you would not get involved in exploiting offshore these [Malvinas] islands. You would automatically be banned," said an embassy source.
Premier, which took over operating the Sea Lion project, at the end of 2012, said considerable work had been done in the first six months of this year on a scheme to produce the first barrels of offshore Falklands oil.
The company said it planned to extract 284m barrels of oil from the north part of the field before moving on to get a further 110m barrels from the south.
The islands have been at the centre of a sovereignty dispute between Britain and Argentina for almost 200 years, with the two countries going to war over it in 1982.
Tension was raised this summer after Argentina's ambassador to London, Alicia Castro, described David Cameron's attitude to the territory as stupid.
Argentinian embassy sources in London said they were frustrated by Britain's refusal to discuss the islands' future despite requests from the UN.
Cameron has publicly rejected Argentina's claims to the territory, saying if its inhabitants choose to remain British he backs them "100%".
