A tired and sombre-looking Pope Francis led a Palm Sunday service before more than 100,000 people, opening two packed weeks of activities including Easter and the canonisation of two popes.

The 77-year-old pontiff appeared tired at the start of the ceremony when he delivered an impromptu homily.

But he later perked up and seemed energised as he greeted young people holding palm branches and was driven around St Peter’s Square. Then he posed for “selfies” with young people from Rio de Janeiro who had carried a large cross in the square.

On Good Friday and Holy Saturday he is due to preside at three services leading up the Easter Sunday, when he delivers his “Urbi et Orbi” (to the city and the world) blessing and message.