David Cameron and German chancellor Angela Merkel have agreed to work together to make the European Union more competitive and flexible, Downing Street has said.
Following talks at Mrs Merkel's guest residence at Schloss Meseberg, No 10 said the two leaders also agreed that the EU should be prepared to make an "ambitious offer" in trade talks with the US.
The Prime Minister used his overnight stay in the Brandenburg countryside to set out his plans to renegotiate Britain's relationship with Europe, but the Downing Street statement offered no clue as to how they were received.
Mrs Merkel is anxious that Britain should remain in the EU and has made no secret of her concerns about Mr Cameron's plan to stage a referendum on continuing membership if the Conservatives win the next general election in 2015.
"On the EU, the PM set out his approach to European reform, following on from his speech in January," the Downing Street statement said.
"They agreed on the urgent need to make Europe more competitive and flexible and talked about ways to achieve this. And they discussed how we can work together in the run-up to the May and June European councils to make further progress."
The two leaders also discussed the forthcoming G8 summit, which Mr Cameron is hosting at Lough Erne in Northern Ireland, and the need to show "global leadership" in tackling tax evasion and aggressive tax avoidance.
On Syria, where Mrs Merkel is resisting pressure from Britain and France to lift an EU arms embargo to allow equipment to go to the rebels, they agreed to keep working to find ways to increase pressure on the Assad regime while strengthening the "moderate" opposition.
In an unusual move seen as evidence of their good working relationship despite their differences on key issues, Mrs Merkel invited Mr Cameron to bring his wife, Samantha, and their three children to stay at Schloss Meseberg, an elegant baroque palace set in picturesque grounds.
Officials say that the two leaders agree that the EU treaties would have to be changed, which Mr Cameron is banking on to renegotiate Britain's relationship, although no agreement was reached on what form the changes would take, or when they would take place.