Pope Francis has been formally installed as Bishop of Rome and has urged lapsed Catholics not to be afraid to return to God.

Pope Francis celebrated a Mass before thousands of people in the Rome Basilica of St John in Lateran.

He formally has taken possession of the cathedral in his capacity as bishop of the Italian capital, his other major role along with the papacy.

Pope Francis, the former archbishop of Buenos Aires, has indicated that he intends to embrace his role as Rome's bishop as well as leader of the 1.2 billion member Catholic Church.

Since his election on 13 March he has referred to himself more often as "bishop" than "pope" and is expected to visit many of Rome's parishes, a practice he maintained in Buenos Aires.

In his homily in St John's, Pope Francis urged Catholics who had strayed from their Church to have the courage to return.

Pope Francis has inherited a Church weakened by sexual abuse of children by priests in many countries and allegations of corruption in the Vatican.

Many have said their faith was shaken by the scandals.

Pope Francis, who is expected to make new appointments to clean up the Vatican's often dysfunctional bureaucracy, urged Catholics to let God back into their lives.