The Queen has called for unity and warned that division between European nations is “dangerous”, ahead of a two-day EU summit in Brussels.
The comments follow heightened tensions with Russia as well as ongoing talks to avert a potential Greek exit from the eurozone.
They also come ahead of a meal which Prime Minister David Cameron plans to use to pave the way for talks over possible reforms, which will begin in the autumn.
The Queen, who is on a four-day state visit with Prince Philip to Germany, made the speech during a state banquet at German president Joachin Gauck’s residence at Bellevue Palace.
German Chancellor Angela Merkel was also present at the banquet.
Mr Cameron hopes to renegotiate the deal that Britain gets as part of the EU, ahead of a referendum on the country’s membership by the end of 2017.
While the issue is not on the formal agenda for the summit in Brussels, the programme for the event makes clear that he will be able to make his point during a meal tonight.
Responding to the Queen’s comments with his own speech, President Gauck stressed that the EU “needs Britain”, and as such it would support a “constructive dialogue” on the reforms requested.