By Domenico Lusi
ROME (Reuters) - Italy's Deputy Prime Minister Matteo Salvini has been put under investigation over possible misuse of state flights while campaigning for European elections at the head of his far-right League party, the Rome audit court said on Thursday.
Prosecutors opened the probe after newspaper la Repubblica said Salvini flew around 20 times for campaign events ahead of the European Parliament vote on May 26.
The 46-year-old Salvini, who is also interior minister, denied any illegal use of public money.
"No abuse, no irregularity, no state or police flights to campaign, but always for institutional commitments," he said in a statement sent by his spokesman.
"I'll have words with anyone who says otherwise."
Recent opinion polls suggest the League could win more than 30% of the vote at the election, making it easily the largest Italian party at the European Parliament, but Salvini has faced growing problems as the campaign draws to a close.
His rallies have been increasingly interrupted by protesters, and some media have labelled him an "absentee minister" who passes far more time campaigning than on duties.
According to La Repubblica, he has spent just 17 full days in the Interior Ministry this year.
Salvini, who portrays himself as a tough-talking, no-nonsense politician, is Italy's most popular party leader, but his unstinting anti-migrant rhetoric polarises public opinion and infuriates his detractors.
He drew accusations of heavy-handed censorship after fire-fighters used a crane to remove a banner saying "you're not welcome" from the upstairs windows of a house in the northern Italian town of Brembate that he visited on Monday.
Following that episode, similar banners have been defiantly exhibited by protesters in towns all over Italy.
In March, Italy's parliament voted to prevent prosecutors from pursuing an investigation into Salvini for abuse of power and kidnapping after he blocked a coastguard ship with 150 migrants aboard for almost a week off the coast of Sicily.
(Additional reporting by Angelo Amante; Writing by Gavin Jones; Editing by Andrew Cawthorne)