PARMA, Italy (Reuters) - A mayor with the anti-establishment 5-Star Movement has been placed under investigation for alleged abuse of office, an embarrassment for Italy’s second-biggest party which has built its success on a squeaky clean image.

Mayor of Parma Federico Pizzarotti, gestures as he talks during an interview with Reuters at his office in downtown Parma, northern Italy March 11, 2013. REUTERS/Alessandro Garofalo

Federico Pizzarotti, the mayor of wealthy northern city Parma, said on Thursday that magistrates were looking into the appointment last year of the head of the local opera house and denied any wrongdoing.

“I am calm about this because it is a formality,” Pizzarotti said in a statement. Being placed under official investigation does not imply guilt and does not necessarily lead to a trial.

Pizzarotti is the second senior 5-Star politician to reveal he has been caught up in a legal investigation in less than a week, putting pressure on the party ahead of municipal elections next month where the group hopes to make major gains.

On Saturday, Filippo Nogarin, the mayor of the Tuscan city Livorno, said he was under investigation for fraudulent bankruptcy in connection with the city rubbish collection company. He has also denied wrongdoing.

5-Star’s political opponents on both the left and the right leapt on the legal probes, accusing the party of hypocrisy for presenting itself as progressive and pure even when its local administrations were coming under judicial scrutiny.

“The truth is that behind their words there is nothing. They govern badly and apply appalling double standards,” said Andrea Romano, a parliamentarian with Prime Minister Matteo Renzi’s Democratic Party (PD), itself the target of many probes.

POWERFUL VOICE

The judicial investigations have targeted the two most important towns that the 5-Star, which was founded in 2009 by comedian Beppe Grillo, has yet to win in local elections.

Opinion polls say it is well placed to make significant gains next month with its mayoral candidate leading the field in the capital Rome. A survey released by Index Research pollsters this week suggested the party had overtaken Renzi’s PD party as the most popular political force in Italy.

Although it has proved a powerful voice in opposition, it has found governing towns at a local level more of a challenge.

Pizzarotti was placed under investigation after a local PD politician complained that his administration had appointed someone to head the Teatro Regio in Parma last year who had not taken part in the official selection process.

Parma prosecutor Antonio Salvatore Rustico told Reuters that Pizzarotti and four other officials had been placed under investigation several weeks ago because the hiring process for the top theater job “seemed a little inconsistent”. He said he would wrap up the inquiry rapidly.

Earlier this year, 5-Star expelled from its ranks the mayor of Quarto, on the outskirts of the southern city Naples, after a police investigation indicated that her administration had been infiltrated by local mobsters. She denied any wrongdoing and accused the party of abandoning her to save its own reputation.