Brussels: The European Commission President has banned EU commissioners from starting talks with the UK until the British government submits its formal request to leave the union. As an emergency EU summit got underway in the European Parliament in Brussels on Tuesday, Jean-Claude Juncker said: "No notification, no negotiation." Juncker urged British Prime Minister David Cameron to formally submit a request to withdraw from the EU. He said there would be no negotiations over Brexit until the UK submits its formal request to withdraw by triggering Article 50 of the Lisbon Treaty. He said the EU cannot continue in "a situation of prolonged uncertainty". Cameron, who campaigned for Britain to remain in the EU, announced on June 24 his plan to step down as leader of his government by October, saying the next prime minister will have to decide whether to trigger Article 50. Juncker expressed sadness at the UK's decision but said the will of Britons must be respected. This remark drew applause from members of the eurosceptic UK Independence Party, led by prominent "leave" campaigner Nigel Farage. Juncker responded by saying that "this is the last time you are applauding here". Juncker said he was surprised to see Farage in the European Parliament, adding "I thought it was you who were fighting to leave the EU". Juncker said he would fight to his "last breath" to preserve a unified Europe, and added that although the British vote had "clipped some wings", the EU will continue to "fly". Addressing members of parliament, anti-EU Farage said: "The reason that you're so angry is perfectly clear: You, as a political project, are in denial." "The UK will not be the last member state to leave the EU," he said. Farage was temporarily interrupted by European Parliament President Martin Shulz, who asked for calm as parts of the UKIP leader's speech drew jeers from other MEPs. Shulz requested they not imitate the behaviour of UKIP members. Donald Tusk, President of the European Council, proposed another summit will be held on September 27 to discuss the UK's withdrawal from the bloc.