Two surfers on motorised boards who were labelled “idiots” by Venice’s mayor for speeding down the city’s Grand Canal have been identified by authorities.

A video was posted on social media by Luigi Brugnaro of the pair heading along the famous Italian waterway after they were caught on camera.

On Twitter, Mr Brugnaro asked for the public’s help to find who he called “two overbearing idiots making a mockery of the city” so they could be punished.

He added that “mayors urgently need to have more powers in terms of public safety”.

And he offered to buy dinner for anyone who identified the surfers.

In a later post, he said their boards had been confiscated and that the two would soon be found.

He did not say what punishment they would face, but the city has a number of rules governing visitor behaviour.

Venice has suffered from over-tourism for years, and with it lapses in decorum by those who take trips there.

In 2019, the city fined two German travellers £830 for making coffee on the 430-year-old Rialto Bridge.

Visitors are also banned from swimming in the canals and from eating on the steps of monuments.

From 2023, day-trippers will have to pay a visitor’s tax to help offset the raised costs of providing services in the city.