The town has thousands of visitors each year who come on a pilgrimage to visit the location of a supposed Marian apparition (a sighting of Mary in the Catholic faith), normally between April and October.
However, pickpocketing has doubled from 117 in the first nine months of 2018, compared to 274 so far in 2019.
According to the local prosecutor Philippe Aurignac, the most risky place is right by the shrine of Mary in the centre of the town.
City councilor Philippe Subercaze told The Telegraph: "The pickpockets are highly organised professionals.
"They arrive in waves and change all the time. As soon as one is identified or arrested, they are replaced. It's a game of cat and mouse."
On a trip to Lourdes, Catholics often visit the grotto where they believe the Virgin Mary appeared to Bernadette Soubirous in 1858, might take part in torch lit processions and visit churches where Bernadette and her family are buried.
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