Ottavia Piana fell during an expedition to map an uncharted branch of the Bueno Fonteno cave near Bergamo

A huge rescue operation was under way north-east of the Italian city of Bergamo to free a caving instructor who became trapped while exploring a cave.

Ottavia Piana, 32, considered an expert spelunker, injured herself after falling 5 metres (16ft) on Saturday evening during an expedition with eight others to map a section of an uncharted branch of the Bueno Fonteno cave. She fell in the same cave system last year, fracturing her leg and remained trapped for 48 hours.