BRUSSELS (Reuters) - European leaders reached a deal on migration in the early hours of Friday after tense and lengthy talks, but the pledges made to strengthen borders were vague and a bleary-eyed German Chancellor Angela Merkel conceded differences remained.

Under the agreement, reached after nine hours of often stormy talks, EU leaders agreed to share out refugees arriving in the bloc on a voluntary basis and create controlled centers inside the European Union to process asylum requests.

They also agreed to share responsibility for migrants rescued at sea, a key demand of Italys new Prime Minister Giuseppe Conte.

Italy is not alone anymore, he said.

Conte, whose government includes the anti-establishment 5-Star movement and far-right League, had earlier refused to endorse a summit text on security and trade until other leaders had pledged to help Italy manage Mediterranean arrivals.

The Brussels meeting underscored how Europes 2015 spike in immigration continues to haunt the bloc, despite a sharp drop in arrivals of people fleeing conflict and economic hardship in the Middle East and Africa.

It took place in an atmosphere of political crisis, with German Chancellor Angela Merkel under intense political pressure at home to take a firmer stance on migration.

Merkel, speaking to reporters at 5 a.m., sought to put a positive spin on the result, saying it was a good signal that leaders had been able to agree a common text on the migration issue.

But she acknowledged that the bloc still had a lot of work to do to bridge the different views.

French President Emmanuel Macron, who has sharply criticized Italy for refusing to allow a migrant rescue ship into its ports, said European cooperation had won the day.

In a final statement full of convoluted language designed to satisfy the divergent views, the leaders agreed to restrict migrant moves within the bloc but made clear virtually all of their pledges would be carried out on a voluntary basis by member states.

They also agreed to tighten their external border and increase financing for Turkey, Morocco and other North African states to prevent migration to Europe.

It was unclear whether the deal would be enough to appease Merkels coalition partner, the Christian Social Union (CSU), which has threatened to shut Bavarias border to migrants. That could trigger the collapse of her three-month-old government as well as the EUs Schengen zone of free travel.