* Wulff resigned in 2012 after scandal erupted
* Acquitted of accepting expenses for hotel, meals at beer festival
* Had been ally of conservative Chancellor Angela Merkel (Adds quotes, details)
By Jan Schwartz
HANOVER, Feb 27 (Reuters) - A German court cleared Christian Wulff on Thursday of corruption charges for accepting roughly 700 euros in expenses at a beer festival when he was a state premier, ending the first trial of a former post-war president.
Once tipped as a future chancellor, 54-year-old Wulff served just 20 months as president before resigning in disgrace in 2012 over favours he accepted two years before he was vaulted into the ceremonial post by his conservative ally Angela Merkel.
His dramatic fall from grace, followed by the separation from his glamorous wife Bettina, has gripped the nation. German presidents have limited power but are expected to serve as a moral compass and adhere to the highest standards of conduct.
"The accused Wulff is acquitted," Judge Frank Rosenow told the court, adding there was insufficient evidence to prove that Wulff had accepted an illegal payments.
The charges stemmed from a 2008 visit to the Oktoberfest beer festival in Munich when Wulff was premier of the state of Lower Saxony and a rising star in Merkel's conservative Christian Democrats (CDU).
Prosecutors argued that Wulff had allowed film producer David Groenewold to cover some of the costs of his hotel stay and meals, amounting to 719 euros. In exchange, they said, Wulff lobbied German conglomerate Siemens to provide financial support for a Groenewold film.
"I am of course relieved that justice has prevailed," a smiling Wulff told reporters outside the court in the northern town of Hanover, adding he wanted to look to the future after a difficult two years. He left quickly, saying he had to collect his young son from kindergarten.
Wulff's credibility as president was eroded after media accused him of misleading the Lower Saxony parliament over a cheap home loan from a businessman friend. A stream of allegations followed about flight upgrades and gifts.
The once popular Wulff made life more difficult for himself by leaving an irate message with the top editor of Germany's Bild newspaper, threatening "war" if it ran a story about his home loan. After weeks of damaging headlines, prosecutors asked parliament to lift his immunity and Wulff quit.
The debacle was an embarrassment to Merkel who had hand-picked the career politician as her candidate for president in 2010, despite other seemingly stronger contenders, including current head of state Joachim Gauck, a widely-respected former East German dissident and rights activist.
Wulff had repeatedly insisted he was innocent and chose to face trial to clear his name rather than agree to an out-of-court settlement.
The scandal over Wulff and his wife Bettina has become the subject of German talk shows and TV dramas.
It underscored the high moral standards to which politicians and public figures are held in Germany. Some foreign commentators have expressed amazement that Wulff was taken to court over a sum of 719 euros.
The last former president to go on trial in Germany was Grand Admiral Karl Doenitz, who was convicted at the Nuremberg military trials for his role in Hitler's Nazi regime and spent 10 years in jail. (Writing by Madeline Chambers; Editing by Noah Barkin)