BRUSSELS, Belgium (AP) — European Union leaders spelled out stark conditions for a new relationship with a departing Britain yesterday, warning that if British business wants to keep access to Europe’s single market, the country must accept European workers, too.

The leaders produced no clear rehaul for their shaken union after an unusual and emotionally charged summit, but agreed they must make it more relevant to citizens and keep it from disintegrating after Britain’s unprecedented vote to leave. The 27 remaining presidents, chancellors and prime ministers said they’re “absolutely determined to remain united,” EU Council President Donald Tusk said.

They met without British Prime Minister David Cameron, who left Brussels on Tuesday night without any clear divorce plan, fending off pressure for a quick exit and punting the complex departure negotiations to his successor. In Britain, nominations opened Wednesday for a new Conservative leader to replace him after his devastating political miscalculation in calling last week’s referendum.

Other EU leaders warned the UK that if it wants to continue to enjoy the seamless single market after its departure, it would also have to accept that EU citizens can continue to enter Britain. That’s the crux of the current tensions: Britain’s “leave” vote hinged on concerns about migration from poorer EU countries.

The leaders emerged from Wednesday’s summit insisting that the “four freedoms” central to European unity are indivisible: the free movement of people, services, goods and finances.

Tusk convened a special EU summit on September 16 in Slovakia’s capital to work out a plan forward to keep the EU united. There’s a widespread sense that the post-war project to foster peace via trade has become a bureaucratic, undemocratic behemoth with little meaning for its 500 million citizens. The initial EU founding nations in the west lean toward a tighter, closer union, while newer nations in the east want to keep more control with national governments — notably of their borders.

To allow the status quo to continue, French President Francois Hollande warned, would benefit populist forces that seek “the end of Europe”. France is among EU countries now facing calls for referendums on quitting the bloc, mainly from the far right.

German Chancellor Angela Merkel said the lesson from Britain’s departure isn’t necessarily either deeper integration or returning more powers to national governments. She said Wednesday: “This is not about more or less Europe as a principle, but about achieving results better.” She said that combating youth unemployment, for example, could involve both scrapping EU directives and deepening European cooperation.

“The coming weeks will be decisive,” Hollande said. “Europe must show its solidity.”

However, the 27 remaining EU members remain divided over how to deal with immigration. Central European nations led by Hungary refuse to accept imposed EU refugee quotas, and countries further north have all tightened border controls in response to the arrival of more than 1 million migrants last year. Britain is more concerned about EU immigration, since its strong economy draws hundreds of thousands of workers from other EU nations.

The shock British vote has roiled markets and will rob the EU of its richest financial market, biggest military power and a diplomatic giant. It could also prompt an unravelling of the UK.

Scotland’s First Minister Nicola Sturgeon met Wednesday in Brussels with European Parliament President Martin Schulz and is meeting later with the leader of the EU executive, Commission President Jean-Claude Juncker. Scottish voters overwhelmingly chose to remain in the European Union but were drowned out by English voters. Sturgeon has indicated there may be a new referendum on Scottish independence.

“It was a good opportunity for me to set out Scotland’s position and Scotland’s desire to remain within the European Union and to protect our relationship with the European Union,” Sturgeon said after meeting Schulz. She added: “I don’t underestimate the challenges that lie ahead for us seeking to find a path.”

Hollande insisted the EU will make no advance deal with Scotland.

Watching Britain’s turmoil, Luxembourg Prime Minister Xavier Bettel said, “With a disunited United Kingdom, we need a united Europe more than ever.”

The economic fallout from the vote has been severe. Ratings agency Fitch expects growth and investment in Britain to fall next year due to uncertainty over the European Union exit. Some businesses are putting investments on hold, and Fitch said, “There is little doubt that the UK referendum vote in favour of leaving the EU will take a significant toll on the economy.”

Vodafone, one of Britain’s biggest companies, will consider moving its group headquarters because of the vote. The company, which says a majority of its customers are in other EU countries, said in a statement yesterday that EU membership had been an important factor in its growth, and that free movement of people, goods and capital were integral to any pan-European business.

“This is the world’s fifth-biggest economy and 15 to 17 per cent of the European Union’s gross domestic product, and if this country leaves the internal market ….then of course that will be a difficult situation,” Merkel said.