EU leaders failed early Friday to narrow the east-west gap over how to deal with migrants coming to Europe and face a big task ahead to reform asylum rules by a deadline of June next year, summit participants said.
During more than two hours of what one called "fierce" debate, eastern European leaders stood firm against refugee quotas which the majority adopted in 2015 as a form of solidarity with frontline states Greece and Italy.
The stubborn divide contrasts with broad agreement among the leaders to continue shoring up Europe's external borders through cooperation deals with third countries like Turkey and Libya.
"Solidarity cannot exist only in the external dimension, but must also exist in the internal one," German Chancellor Angela Merkel told reporters following the summit.
"Here we still have a lot of work to do. The points of view did not change. But there is a clear task to continue working until June next year," Merkel said.
European Council President Donald Tusk irked some nations when he said in a pre-summit letter that a mandatory quota scheme for relocating refugees from frontline states was "ineffective" and "highly divisive".
Eastern European states Poland, Hungary, Slovakia and the Czech Republic have backed his approach, but Germany and others say the quotas are a necessary way of showing solidarity in the EU.
Merkel's 2015 decision to open the doors to one million asylum seekers was blamed by a number of European leaders, particularly Hungary's Viktor Orban, for worsening the migration crisis.
The quotas triggered sharp east-west division when they were adopted at the height of the migrant crisis in 2015 as a way to ease the burden on Italy and Greece, which have had more than 1.5 million people land on their shores in the last three years.
The EU has since stalled on plans for a permanent mechanism for future crises, and the leaders of Poland, Hungary, the Czech Republic and Slovakia made clear their continuing opposition.
"The discussion was fierce because the differences of opinion are still wide," Dutch Prime Minister Mark Rutte said after the long dinner talks.
"There's no solution on how to find a consensus on the quotas," Rutte said.
Luxembourg Prime Minister Xavier Bettel told reporters afterwards "it is dangerous to think we can do without a permanent mechanism".
Before the summit started, the four eastern leaders offered a financial contribution of 35 million euros ($30 million) to bolster external borders.
But Bettel, Rutte and others said the money cannot buy off countries that do their share to admit migrants and refugees.
"What Orban is doing is shameful!" Dutch Prime Minister Mark Rutte said at the end of the summit.
"If you allow that to happen, the EU becomes a place where each one does his shopping to buy what he likes," Rutte added.
- 'Decide by majority' -
Orban has led eastern opposition to admitting refugees and migrants, saying the region will not be able to integrate them and it will face a security threat, particularly from Muslims.
EU sources said there is a "window" to try to bridge the gap over sharing the migrant burden as the bloc has been under less migrant pressure for the last year or so.
The June deadline for asylum reform comes as the summer weather makes Mediterranean boat crossings more likely.
Italy and Greece have seen sharp declines in migrant arrivals in the last months and year as a result of EU cooperation with Libya and Turkey, but fear future crises.
Tusk's comments caused a pre-summit row with the European Commission, the executive arm of the EU, which first pushed the quota system.
EU officials said over 32,000 people had been relocated under the plan, or 90 percent of those eligible. The scheme was originally meant to relocate 160,000 refugees.
EU Migration Commissioner Dimitris Avramopoulos called Tusk's remarks "unacceptable" and "anti-European".
After the summit, Rutte said: "We are worried about (Tusk's) consensual approach.
"It is important that as a last resort the council (member states) can decide by majority."