* New party backing German euro exit to have first meeting
* Wants return to Deutschmark to escape others' "mistakes"
* Mainstream parties still pro-euro despite bailout concerns
* Merkel still on course to win most votes in Sept election (Adds analysts, more background)
By Gareth Jones
BERLIN, March 11 (Reuters) - One in four Germans would be set to vote in September's federal election for a party that wants to quit the euro, according to an opinion poll published on Monday that highlights German unease over the costs of the euro zone crisis.
Germany's mainstream parties remain solidly pro-euro despite grumbling over costly bailouts of Greece and others. A German taboo on nationalism, rooted in atonement for the crimes of the Nazi era, has helped to muffle eurosceptic voices.
But the poll conducted by TNS-Emnid for the weekly Focus magazine showed 26 percent of Germans would consider backing a party that wanted to take Germany out of the euro and as many as four in 10 Germans in the 40-49 age bracket would do so.
The survey, which canvassed the views of 1,007 people on March 6-7, coincides with the launch of a new party, Alternative for Germany (AfD), that calls the euro a "fatal mistake", though political analysts play down its election chances.
AfD and other German critics of the euro say it is unfair and undemocratic to expect Germany to bear the costs of other countries' economic mistakes and call for a return to the Deutschmark. "Every people should be able democratically to decide its own currency," the AfD said on its website.
Emnid chief Klaus-Peter Schoeppner said the survey results were partly a signal from conservative supporters of Chancellor Angela Merkel's coalition that they expected a strong defence of German interests in Europe and would not accept any moves towards "euro bonds", a sharing of liability for euro zone debt.
"There is scope in Germany for a protest party to win two or three percent support but it would be very difficult for it to enter parliament," he told Reuters, adding that much would depend on the wider economic situation.
A political party needs to win 5 percent to get seats in Germany's Bundestag, the lower house of parliament.
Despite the euro zone crisis, which has pitched southern Europe into deep recession, Germany, the region's largest economy, is faring relatively well, its exports to non-European markets are booming and unemployment is near two-decade lows.
GERMANY "IN CRISIS"?
The new eurosceptical party, the AfD, comprising mostly academics and business people, is due to hold its first meeting on Monday evening in a suburb of Frankfurt.
"Let's put an end to this euro!" reads the message on the front page of its new website at www.alternativefuer.de.
"The Federal Republic of Germany is in the deepest crisis in its history. The introduction of the euro was a fatal mistake that is threatening our prosperity. The old parties are grizzled and worn out. They are stubbornly refusing to admit their mistake and correct it," it said.
The AfD said the European Central Bank should not be allowed to buy up the debt of struggling euro zone members. It fears this could stoke inflation that will destroy the value of Germans' savings.
But previous eurosceptic parties in Germany have made little headway. One of them, the "Free Voters", have won seats in Bavaria's regional assembly but have yet to win support at the national level.
Gero Neugebauer, a political scientist at Berlin's Free University, said AfD was unlikely to gather much momentum because it was effectively a single-issue party and that Germans had more pressing concerns than the fate of the euro.
"Most of those who talk about the dangers of the euro and long for a return to the Deutschmark will still vote conservative in the end. They believe Merkel will protect them, they feel safer with her than voting for a new party," he said.
Merkel's conservatives are tipped to win most votes in the September election, helped partly by her tough stance on euro zone bailouts and her insistence that heavily indebted countries embrace harsh austerity measures.
The main opposition centre-left Social Democrats and Greens have broadly backed Merkel's efforts to tackle the euro crisis.
The crisis has featured less on the front pages of German newspapers since the European Central Bank pledged last summer to buy up unlimited quantities of sovereign debt if necessary - in return for strictly binding austerity commitments - to save the European common currency.
But many Germans, including at the Bundesbank, are deeply uncomfortable with this ECB pledge and last month's inconclusive election in Italy, where anti-austerity parties performed well, has reminded Germans that the crisis is far from over.
(Reporting by Gareth Jones; Editing by Noah Barkin and Mark Heinrich)