A storm-tossed tree branch which hit Swiss power lines helped trigger a massive blackout covering almost all of Italy, trapping thousands on trains and forcing the Pope to use a back-up generator to proclaim his new cardinals.

A MASSIVE blackout in Italy, which left millions of people without power, stranding planes and trains, and leading to traffic accidents was last night blamed on a tree.

A massive power blackout which crippled Italy and left most of its 57 million people without electricity for hours was today blamed ... on a tree.