Indignant European Union lawmakers pressed Britain to end the uncertainty that has gripped European and global markets, saying Tuesday that if it intends to leave, it should start the process immediately.British Prime Minister David Cameron entered talks with European Commission President Jean-Claude Juncker hours ahead of an EU summit that is expected to hear from British leaders that exit talks might not be launched before October. Cameron has said he wants informal talks on what comes next before that happens.In an unprecedented emergency session of European Parliament called after Britain voted Thursday to leave the union, Juncker demanded that Britain clarify its future. "I want the U.K. to clarify its position. Not today, not tomorrow at 9 a.m., but soon," he told lawmakers. "We cannot allow ourselves to remain in a prolonged period of uncertainty."Juncker said he had banned his policy commissioners from holding any secret talks with Britain on its future until London triggers the exit clause. "No notification. No negotiation," he said to resounding applause.German Chancellor Angela Merkel said she will use "all her strength" to prevent the EU from drifting apart. She and other EU leaders were beginning a two-day summit later Tuesday to hear Cameron's position and chart the way forward.Britain's "leave" leaders hope that the nation can still enjoy many perks of the EU's internal market for business while being able to deny EU citizens entry to Britain to address concerns about immigration that were a key factor in the vote. Merkel, head of the EU's biggest economy, made clear that is not an option. In an address to German parliament before heading to Brussels, Merkel said she expects that Britain will want to maintain "close relations" with the EU once it leaves, but warned it cannot expect a business-as-usual approach."Whoever wants to leave this family cannot expect to have no more obligations but to keep privileges," she said. "We will ensure that the negotiations are not carried out with the principle of cherry picking."She and other leaders joined Juncker in saying there can be no talks with Britain until it starts the formal procedure to leave. Lawmakers paid tribute to Britain's commissioner in Brussels, Jonathan Hill, who resigned after last week's vote. He wept in parliament on Tuesday as he received a standing ovation.Ahead of Tuesday's summit, French President François Hollande urged Britain to "not waste time" in leaving the bloc while Italian Prime Minister Matteo Renzi told his country's Senate: "The last thing Europe needs is to start a year-long discussion on [negotiation] procedures."After the Brexit, fears of a rise of Euroscepticism and anti-establishment parties in Europe have deepened. French far-right National Front leader Marine Le Pen called for a "Frexit" shortly after the results of Britain's membership referendum were announced. Similarly, Geert Wilders, the leader of the Dutch, anti-Islam, far-right Freedom Party (PVV), called for a "Nexit" and other politicians in Austria, Sweden, Finland, Denmark have also floated similar ideas to leave the EU.