Authorities in China have launched a big security operation to try to end a wave of unrest caused by Tibetan campaigners.

In the past year, at least 19 people have publicly set themselves on fire, five in the past week alone, in a campaign calling for more freedom for Tibetans.

China has exercised sovereignty over Tibet for more than six decades.

Damian Grammaticas has been to Sichuan province bordering Tibet where most of the trouble has happened.

Warning - this video contains images which some may find distressing.