FRANKFURT: Europe will defend the single currency in the event of fresh market tensions, including beefing up the euro zone's rescue fund if necessary, German Deputy Finance Minister Joerg Asmussen said.

Speaking at the Kapitalmarktforum banking conference, Asmussen said the ongoing crisis was down to problems of individual countries rather than the euro currency, sounding a note of caution about the recent improvement in debt markets.

"Markets have been calm since the start of the year. The question is how long this will last," he said.

In an interview with CNBC after his speech, he said Germany and euro zone leaders were ready to respond if market sentiment turned negative again.

"If there are market developments, which I don't see right now, then we have to look at what we can do," Asmussen said.

"We have always said that we would do all that is necessary to defend the stability of the euro zone as a whole. That might include revising the scope and efficiency of the EFSF