British Prime Minister David Cameron gathered his Cabinet on Monday at the start of a crunch week for Europe's leaders after the country's shock vote to leave the EU, seeking to head off further turmoil. Finance minister George Osborne also broke his silence and tried to reassure financial markets following the momentous Brexit vote, which has fueled fears of a break-up of the United Kingdom with Scotland vying for independence. Osborne said on Monday the country's economy was strong enough to cope with volatility caused by its vote to leave the European Union, whose leaders demanded a quick divorce and promised no special treatment. Speaking publicly for the first time since the vote, British Chancellor George Osborne said he was working closely with the Bank of England and officials in other leading economies for the sake of stability as Britain reshapes its relationship with the EU. "Our economy is about as strong as it could be to confront the challenge our country now faces," he told reporters at the Treasury. "It is inevitable after Thursday's vote that Britain's economy is going to have to adjust to the new situation we find ourselves in." Boris Johnson, a leading proponent of a Brexit and likely contender to replace Prime Minister David Cameron who resigned on Friday, praised Osborne for saying "some reassuring things to the markets." US Secretary of State John Kerry arrived in London on Monday after a stop-off in Brussels, while the leaders of Germany, France and Italy met in Berlin. Three days after Cameron announced his resignation, opposition Labour leader Jeremy Corbyn is also facing pressure to stand down, with a string of his top team resigning on Sunday. EU powers have called for a swift divorce amid fears of a domino effect of exit votes in euroskeptic member states that could imperil the integrity of the 28-nation alliance. But Cameron has said negotiations on Britain's departure must wait until a successor is chosen from his Conservative party, which could be as late as October. European Parliament chief Martin Schulz warned on Sunday that a period of limbo would "lead to even more insecurity" and said a summit of EU leaders on Tuesday, which Cameron will attend, was the "right time" to begin exit proceedings. But EU diplomats warned on Sunday that Britain "may never" trigger the formal divorce process — Article 50 of the 2007 Lisbon Treaty, which will set the clock ticking on a two-year period for Britain to negotiate its divorce. Many European leaders want rapid action, and say there is no going back on the vote. "France like Germany says Britain has voted for Brexit. It should be implemented quickly. We cannot remain in an uncertain and indefinite situation," French finance minister Michel Sapin said on France 2 television. Guenther Oettinger, a German member of the EU's executive European Commission, also issued a warning. "Every day of uncertainty prevents investors from putting their funds into Britain, and also other European markets," he told Deutschlandfunk radio. "Cameron and his party will cause damage if they wait until October." Kerry, in Rome for talks, expressed regret at Britain's decision to become the first EU nation to leave the bloc — and vowed Washington would maintain close ties with the 28-country alliance. "Brexit and the changes that are now being thought through have to be thought through in the context of the interests and values that bind us together with the EU," he said. Britons cast aside warnings of isolation and economic disaster to vote 52 percent to 48 percent in favor of quitting the EU in last Thursday's referendum. — Agencies