Italian authorities are searching for a British man who has gone missing after reportedly diving into Lake Como to rescue a teenager.

The man was attempting to rescue two people – a father and son – who were in distress in the water near the San Siro municipality on the lake's western shore on Monday afternoon, Italian media report.

The man and the family he was friends with had reportedly been on a boating trip at the time. The father and son were later rescued by another passing boat, but the man has not been seen again.

The UK Foreign Office said: "We are supporting the family of a British national missing in Italy and are in contact with the local authorities."

Emergency services – including a helicopter, divers and boat units – have responded at the scene, where the lake's depth can reach more than 200m, according to Italian news agency Ansa.

Rescuers are now preparing to deploy two underwater robots to scan the lake bed where the lake becomes too deep for divers, local news site Qui Como reports.

The alarm was first raised around 13:30 local time (11:30 GMT) by the mother of the teenager, who was on a rented boat around 600m from shore with her other child, it said.

The man – who dived in after the father and son after they experienced difficulty swimming and was described as being in his late 30s – began to sink and was not seen resurfacing, the local newspaper reports.

The mother then called emergency services. The father and son were given medical treatment after suffering from the early stages of hypothermia, according to Qui Como.

Lake Como, around 30 miles north of Milan, is a popular tourist hotspot, with more than 78,000 foreign visitors in 2024, local chamber of commerce research shows.

However, water temperatures there can start to fall from September onward.