Greek officials are searching for a US tourist who went missing after going on a hike alone on the island of Amorgos.

Local officials say Albert Calibet, 59, has been missing since Tuesday afternoon. His friend reported him missing when he did not return from his hike.

Several agencies are participating in the search for Mr Calibet, including volunteers from the coastguard and teams from the neighbouring islands of Paros and Naxos, according to Greek public broadcaster ERT News.

His disappearance comes days after the British television presenter Michael Mosley went missing on the Greek island of Symi, where his body was found four days later.

The BBC has contacted the US state department for comment.

Officials are searching both land and water in an area covering almost a quarter of Amorgos, the island's Mayor Eleftherios Karaiskos told ERT.

They have been using a drone to search the northern part of the island and are also attempting to trace Mr Calibet's two mobile phones. Calls to Mr Calibet - who the mayor said had visited the island before - have gone unanswered.

"We’re almost on three days here," his brother Oliver Calibet told Fox 11 TV in Los Angeles. "There’s no water… I’m very distraught."

The island's mayor said the hike on which Mr Calibet had embarked was busy and not particularly challenging, which suggested that the American may have changed from his planned route.

Mr Calibet, described as a retired police officer from Los Angeles County, started a four-hour hike at about 7:00 local time (00:00 EDT) on Tuesday in the village of Aegiali, according to local news outlets.

A few minutes later he is thought to have sent a text message with a picture of the sign showing the route he was taking to Katapola, an estimated four hours on foot.

At around 09:00, a local woman said she spoke to the missing tourist after he bought drinks from a nearby store. Sofia Liviaki told Mega TV that Mr Calibet had drunk a soft drink, showed her his planned route and taken a bottle of water with him for the remainder of his journey.

Mr Calibet's disappearance has shocked the local community on Amorgos, where he has been a regular visitor for a number of years. While the path he chose is well traveled and not difficult, the island has been experiencing a heatwave with temperatures currently as high as 35C.

"Temperatures are very high, like all of Greece during the heatwave," the island's deputy mayor for tourism, Popi Despotidi, told Greek media. "We're guessing he felt dizzy... and collapsed somewhere. It's odd because he's not someone who was walking this route for the first time."

The search for the missing man comes just days after officials spent days scouring another Greek island, Symi, for Dr Mosley, a famous British TV doctor who vanished after setting out on a walk from a beach.

His body was found in a rocky area, and investigators concluded that he died of natural causes the day he went missing.