In the wake of its vote to leave the European Union, Britain must renegotiate its access to the markets of the rest of the world, as well as those of the grouping it is leaving.
It is a huge task for the world’s fifth-biggest economy.
But at the G20 summit in the Chinese city of Hangzhou, Juncker told reporters: “I don’t like the idea that member states of the EU, including those who are still a member state of the European Union, are negotiating free trade agreements.”
Such discussions were an “exclusive matter” for the European Union on behalf of its members and “we are sticking to it”, he told reporters.
Juncker was speaking after Australian Prime Minister Malcolm Turnbull said he was about to launch talks with Britain’s Prime Minister Theresa May on free trade, in what would be one of the first such negotiations following the Brexit vote.
“We’ve got things moving towards having a free trade agreement with the UK,” Turnbull said in Hangzhou.
“Prime Minister May and I are very committed to having an early free trade agreement put in place so that when Britain leaves the EU, we have very open markets between Australia and Britain.”
He added that Australia was providing Britain with “as much assistance as we can at a technical level” for negotiations, noting that London “has not negotiated a trade agreement for a long time” because of its EU membership.
According to EU officials, formal negotiations with Brussels itself cannot start until London triggers Article 50, the treaty provision governing its departure from the grouping.
US President Barack Obama said at a joint briefing with May that they had discussed trade and both countries aim to “ensure that we don’t see adverse effects” in their commercial ties.
It was “already a very strong and robust economic relationship that can become even stronger in the future”, he said.
May said that following Brexit “we will be looking to establish new trading relationships around the globe”.