The undersea quake had a depth of just 12.5 kilometres (7.7 miles) and struck northwest of the enclave's administrative capital of Karyes, the institute said on its website.

A fire department source in Athens said the area's four fire engines had been sent out in search of possible damage.

A local official in Karyes said there were no immediate reports of damage.

Mount Athos, an Orthodox spiritual centre since 1054, has enjoyed an autonomous statute since Byzantine times.

Known as the Holy Mountain in Greece, the community has around 20 inhabited monasteries that are hundreds of years old.