A third of Germans have little or no trust in the strength of the euro, according to a survey published on Thursday on the eve of an EU summit aimed at ending a debt crisis that threatens the survival of the common currency.

The poll, conducted by TNS Infratest for Europe's largest insurer Allianz , showed 30 percent of Germans trusted the currency while 36 percent had some trust in it. Support for the euro was strongest among older Germans.

Allianz said it was the first time the question of trust in the euro had been included in its money trends survey, so it could not provide comparative figures.

A separate poll published in October showed 54 percent of all Germans would like to bring back the Deutsche mark, a number that has remained broadly stable as the euro zone debt crisis has deepened over the past year.

Chancellor Angela Merkel, who joins other European Union leaders for the two-day summit opening in Brussels on Thursday evening, has vowed to defend the euro despite spiralling debt problems in countries such as Greece that have tipped the 17-nation currency bloc into crisis.

The Deutsche mark was a symbol of West German stability and economic strength in the decades after World War Two and former Chancellor Helmut Kohl struggled to convince the public of the benefits of the euro in the 1990s before its introduction.

But euro defenders argue that Germany's export sector, a key driver of growth in recent years, has benefited from the common currency by making its products more competitive abroad than they would have been with a stronger German mark.

The Allianz poll, which canvassed 2,200 people from November 12 to November 19, also highlighted Germans' inflation worries which underlie Merkel's refusal to back calls for the European Central Bank to print money to end the debt crisis.

Nearly 90 percent of those surveyed said they feared an increase in the cost of living. Two thirds said saving was important or very important for them.

A poll published in France this week showed that more than one in three French voters would like to abandon the euro and return to the franc. A majority viewed the euro as a handicap.

(Reporting by Gareth Jones; Edited by Richard Meares)