Lourdes, France - More than 150,000 people gathered in the southern French pilgrimage site of Lourdes on Sunday as Pope Benedict XVI celebrated a Mass to commemorate the 150th anniversary of the appearance of the Virgin Mary to a young peasant girl.

The open-air Mass was the symbolic high point of the 81-year-old pontiff's four-day visit to France, his first since he was elected to succeed the popular John Paul II in April 
2005.

As he did in Paris on Saturday, the pope used the occasion to try and attract young people to the priesthood.

"For your part, dear young people, do not be afraid to say yes to the Lord's summons when he invites you to walk in his footsteps," Benedict XVI said in his homily.

"To those among you whom he calls to follow him in the priesthood or the religious life, I would like to reiterate all the joy that is to be had through giving one's life totally for the service of God and others."

The number of priests in fiercely secular France has been steadily declining, and the church here was hoping that the pope's visit would help reverse the tendency.

On Saturday, after arriving in Lourdes from Paris, the pope was visibly moved as he followed the Jubilee Way, which visited several stations in the life of Bernadette Soubirous, the miller's daughter who at the age of 14 said she had seen the Virgin Mary 18 times in a grotto just outside Lourdes in 1858.

These stops included the church where she was baptized, the house in which she lived with her family and the Grotto of Massabielle.

"When we follow the Jubilee Way in the footsteps of Bernadette, we are reminded of the heart of the message of Lourdes," Benedict XVI said on Sunday in his homily.

"The power of love is stronger than the evil which threatens us. It is this mystery of the universality of God's love for men that Mary came to reveal here, in Lourdes."

Lourdes has become one of the most popular Christian pilgrimage sites in the world, with an estimated 6 million visitors from all over the world expected this year, many of them coming to pray for a miraculous cure for their illness.

On Monday, before returning to the Vatican, Benedict XVI is to celebrate a Mass for the sick in front of the Basilica of Our Lady of the Rosary in Lourdes. (dpa)