German Chancellor Angela Merkel has backed David Cameron's EU reforms, arguing "Europe as a whole will gain" from some of the proposals.
Speaking in Hamburg, Mrs Merkel said she was confident of a deal being agreed for Britain's renegotiated position in the EU.
Making his final push for a reformed EU during a major speech at the same event, Mr Cameron insisted the UK is "an open nation".
Mr Cameron, who gave his last speech before crunch EU talks next week, told the gathering that Britain will not "pull up the drawbridge and retreat from the world" and his aim is "to keep Britain inside a reformed European Union". But he insisted the EU needs to change.
Mr Cameron called on Germany to work with the UK to reform Europe in a way that can "deliver prosperity and security for us all."
Before Mr Cameron gave his speech, Mrs Merkel also addressed the St Matthew's day banquet.
She said she would like the UK "to remain an active member of a successful European Union."
"The way the talks have progressed so far are putting me in a confident mood," said Mrs Merkel.
She said Britain remaining in the EU would be in the interests of Germany and the UK.
Some concerns Mr Cameron has raised are "not only reasonable, but also supported by us (Germany)," Mrs Merkel said.
Every member state should be in the position to "maintain the strength" of its social security system, she said, adding that such issues were not only British.
"Quite the opposite, when we can succeed in pouring these issues into a European mould, I think that Europe as a whole will gain," said Mrs Merkel.