ROME (Reuters) - Defence Minister Lorenzo Guerini called on Tuesday for an investigation into allegations of widespread sexual harassment of women during a rally involving one of Italy's most famous army regiments, the Alpini.

       Rights groups have said that dozens of women reported being verbally abused, wolf-whistled and groped at the May 5-8 event in the Adriatic resort of Rimini, which drew hundreds of thousands of onlookers along with an estimated 75,000 veterans and currently serving members of the Alpini.

       "The conduct some women reported is very serious. These episodes will certainly have to be investigated by the competent authorities," Guerini said in a statement.

       "There must be zero tolerance. Harassment and violence must never, under any circumstances, be justified and must be condemned without hesitation," he added.

       The Alpini infantry were set up in the 19th century to defend Italy's northern, mountainous borders. Its soldiers are instantly recognisable on parade for wearing a black feather pinned to their hats.

       The veterans' body that organises the popular annual get-togethers condemned the "reported uncivilised behaviour", but said some sort of problems were to be expected at events that draw huge crowds of onlookers.

       "When hundreds of thousands of people gather in one place to celebrate, it is almost physiological that rude behaviour can occur," the Alpini National Association said in a statement.

       It also questioned whether its members were to blame, saying anyone could buy fake Alpini hats.

       (Reporting by Angelo Amante; Editing by Crispian Balmer and Alison Williams)