Videos posted on social media showed riot police clubbing unarmed young protesters among about 100 people at a pro-Palestinian demonstration in Pisa, central Italy on Friday.

In an unusual intervention by Italy’s constitutionally apolitical head of state, President Sergio Mattarella issued a statement saying that “with young people, using truncheons is an expression of of failure”.

Mattarella’s office said he told Interior Minister Matteo Piantedosi that “the authority of the police is not measured in batons but in its ability to ensure security while protecting, at the same time, the freedom to express opinions publicly”.

Prosecutors in Pisa have opened an investigation and are looking into the behaviour of more than a dozen officers, according to media reports.

At a meeting with trade union leaders on Monday, Piantedosi promised an internal investigation into what he called “isolated cases”.

But Maurizio Landini, head of the CGIL trade union, told reporters: “There do not need to be many such cases for it to be serious.

“The fact that young people aged 15 and 16 were hit or beaten because they were protesting is in itself serious.”

Pier Paolo Bombardieri, head of the UIL union, added: “We asked for a clear identification of those responsible… of the chain of command.”

The interior minister said 1,076 protests have taken place in Italy since the Hamas-Israel war began on October 7, and only 33 have degenerated into scenes such as those in Pisa.

Prime Minister Giorgia Meloni has not commented, although members of her post-Fascist Brothers of Italy party have defended the police.

MP Giovanni Donzelli offered the government’s “full support” to those in uniform who defended Italians, “beyond the specifics of individual cases and any eventual errors that will be clarified”.

Meloni’s government has been supportive of Israel’s right to defend itself but Foreign Minister Antonio Tajani said this month that its assault on Gaza following the unprecedented Hamas attacks was “disproportionate”.