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

The local coastguard said the man, in his late thirties, had been attempting to rescue two people – a father and his 16-year-old son – who were in distress in the water near the lake’s western shore on Monday afternoon, local officials said.

The man, who was friends with the family, had been on a boating trip with them at the time, the coastguard said. The father and son were later rescued by a 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.”

A helicopter, divers and boat units from the fire department, coastguard and state police have been drafted into the search.

As the lake’s depth can reach more than 250m in the search area, rescuers were also preparing to deploy two underwater robots to scan the lake bed where the lake becomes too deep for divers, the Italian Coast Guard said in a statement.

The alarm was first raised around 13:30 local time (12:30 BST) on Monday, when the man noticed his friend and the boy experiencing difficulty swimming and jumped in to help them.

The teenager’s mother, who had remained on the boat with her younger son, called the emergency services when she saw the man sinking beneath the surface.

The father and son were transferred to a coastguard boat that had responded to the call and were given medical treatment after suffering from the onset of hypothermia, officials said.

The mother and younger son, who were at this point adrift around 600m from shore, were then brought back to land.

The coastguard earlier said that it had been the father who had jumped in to save the boy and the 37-year-old man, before revising its statement of events.

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.