Shares in British oil and gas firm Rockhopper Exploration fell after Argentina threatened to impose sanctions on companies drilling off the Falkland Islands.

Warning Argentina would reclaim the British territory, president Javier Milei said the Sea Lion oilfield owned by Rockhopper and Israeli partner Navitas Petroleum represented a ‘clear and present danger’.

‘If we do not act swiftly, in a few months they will have the material capacity to access the oil that lies underneath our sea,’ Milei said.

Shares in Rockhopper, which is named after the region’s Rockhopper penguins, fell 6.4 per cent.

Rockhopper and Navitas are due to begin extracting oil within two years, which Milei said Argentina could not allow.