The foreign secretary will also travel to Peru and Chile during the trip, which is aimed at showcasing Britain’s internationalist credentials after Brexit.
Relations with Buenos Aires over the Falklands, which Argentina calls the Malvinas, and to which it still lays a territorial claim, have thawed under the regime of Mauricio Macri, whom Johnson will meet.
The first talks about fishing rights since the 1982 Falklands conflict recently took place, and Britain has been helping relatives of some of the more than 600 Argentine casualties to identify remains on the islands.
Speaking ahead of the visit, Johnson said: “This will be my first visit to the region since becoming foreign secretary. Latin America is a vibrant and dynamic part of the world that works closely with the UK on a number of issues including trade, security, science, infrastructure and education.
“I am looking forward to strengthening the UK’s relationship with countries in the region.”
After a week in which he was forced to make concessions in the cabinet battle over the Northern Irish border, Johnson also hopes to get back on the front foot by highlighting the trading potential for British companies in Latin America.
Chilean villagers claim British appetite for avocados is draining region dry
Just 1% of imports to the region currently come from the UK, and Johnson shares the belief of the Brexit secretary, David Davis, that distance is less of a drag on international trade when much of it is in services, such as consultancy and finance.
However, Argentina has been rocked by a sell-off in the currency and debt markets in recent weeks, and earlier this month was forced to open negotiations with the International Monetary Fund about a potential emergency credit line.
Buenos Aires is also unable to strike independent bilateral trade deals, as it is part of Mercosur, a trading bloc that also includes fellow agriculture giant Brazil.
Mercosur has been trying to negotiate a bilateral trade deal with the European Union for 20 years: the EU hopes to sell more cars into the region, while Mercosur’s farmers are pushing for lower tariffs on their beef.
Johnson will also attend the G20 foreign ministers’ summit in Buenos Aires. The trip comes after a bruising week in which Johnson lost the argument over how far Britain should be prepared to go to avoid a hard border in Northern Ireland.
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