Angela Merkel has told David Cameron not to threaten her with the prospect of British exit from the European Union, amid a disagreement over who should be the next president of the European Commission.
The prime minister is attempting to block former Luxembourg prime minister Jean-Claude Juncker from securing the top job in Brussels. The British government is worried he is too keen on further EU integration and would frustrate its attempts to negotiate looser membership terms for the UK.
However Juncker is the preferred candidate of the German chancellor and she reiterated her support for him during a joint press conference in Sweden with Cameron on Tuesday morning.
In an embarrassing public rebuke, Merkel told Cameron that "threats" were not part of the "European spirit" that EU leaders should live up to.
It was recently reported that Cameron told Merkel it was possible the appointment of the federalist Junker would lead to British voters choosing to leave the union.
Juncker is the candidate of the centre-right European People's Party (EPP) - the largest grouping in the European Parliament following last month's elections. Under the Lisbon Treaty, the European Council - made up of the leaders of the member states - is supposed to "take into account the elections to the European Parliament" in choosing a candidate for the presidency, who must then be approved in a vote of MEPs.
But Cameron is seeking to secure enough allies to form a blocking minority in the Council against Juncker under the qualified majority system, which gives added weight to the votes of bigger countries.
Cameron joins Merkel as well as the Swedish and Dutch leaders in a joint press conference
In today's press conference, alongside the Swedish and Dutch prime ministers as well as Cameron, Merkel said she had made herself "clear" that she was in favour of Junker's appointment.
"But when I made that statement in Germany I also made the point that we act in a European spirit . We always do that. Otherwise we can't arrive at a compromise," she said.
"We cannot just consign to the back-burner the question of European spirit. Threats are not part and parcel of that spirit, that's not how we usually proceed."
Cameron, who joined the three other leaders yesterday to row around the lake in Swedish prime minister Fredrik Reinfeldt's boat, made clear that he was hoping for the support of his like-minded northern Europeans in driving forward EU reform.
Addressing the suggestion he had made threats, Cameron said he took a "very straightforward approach" to the negotiations over who should be the next leader of the European Commission.
"The decision about whether to stay in Europe or to leave will be for the British people in a referendum by the end of 2017. Obviously the approach that the EU takes between now and then will be very important," he said.
Reinfeldt said the four leaders had agreed that the EU's future direction must be set before any decisions are made on appointments to top jobs - suggesting that the choice of the new Commission chief remains far from concluded.
Caption Competition: What Are Cameron And Merkel Rowing About?