BERLIN — Britain will remain an important member of the European Union, German Chancellor Angela Merkel said Wednesday, despite refusing to join a new treaty that will strengthen the bloc in its bid to overcome the eurozone debt crisis.

Merkel, the leader of Europe's biggest economy, told Parliament that there is no quick fix to the 17-nation currency bloc's crisis, but she stressed that it offers an opportunity to achieve an ever more integrated union.

"The vision of a genuine political union is beginning to take shape," she said, praising the outcome of last week's EU summit to create a new treaty that moves the bloc toward tough debt ceilings and more fiscal integration.

"The opportunities lying in this crisis are many times greater than its risks, that is my conviction," the chancellor told lawmakers. The new sense of shared responsibility and destiny across the eurozone and the EU's other 10 members "will far outlast this crisis," she added.

But British Prime Minister David Cameron blocked Merkel's push to bring all 27 EU members closer together for treaty changes last week in Brussels, leaving London isolated and forcing others — perhaps all 26 remaining members — to forge a new pact outside the official EU treaties.

Merkel said that, while she regrets the decision, "it is beyond doubt for me that Great Britain will in future continue to be an important partner in the European Union."

Britain "is a reliable partner for Europe not just in questions of foreign and security policy ... (It) is also this partner in many other questions — in competitiveness, in the internal market, for trade, for climate protection," she said.

Cameron's move also has been disputed within his own coalition government, with Deputy Prime Minister Nick Clegg calling the decision "bad for Britain."

Clegg has warned "there is a danger that the U.K. will be isolated and marginalized within the European Union," adding that Britain is "retreating further to the margins of Europe."

Merkel stressed that the new treaty was open to all members prepared to join — cautiously alluding to hopes that Britain might eventually follow suit — and should be merged with the EU's official treaties as early as possible.

There are no easy solutions and there will be setbacks in the long battle to tackle the crisis, Merkel said. "What is crucial is not the duration; what is crucial is whether we will allow setbacks to discourage us or not."

Merkel vowed that Europe would not only overcome the debt crisis, "but Europe will emerge stronger from it than when it entered the crisis."

Geir Moulson contributed to this report.