An elderly woman has been killed in fierce flooding that has closed one of Catholicism's holiest shrines - the Grotto of Lourdes in southwest France.

The 70-year-old woman, who was not named, was trying to get out of her car when it was washed away by floodwaters in the village of Pierrefitte-Nestalas in the Pyrenees south of Lourdes. Her husband was rescued by firefighters.

Heavy rains have swollen the Gave de Pau River, leading to numerous road closures and a putting a severe strain on emergency services.

"We need more reinforcements in the area to face these floods, which are exceptional," interior minister Manuel Valls said.

Two thousand people were evacuated including hundreds of worshippers who made the pilgrimage to the holy grotto.

It is visited every year by six million believers, many gravely ill, who seek a miracle cure.

But deep floodwaters meant that this year the area had to be shut down by authorities. Mayor Jean-Pierre Artiganave told BFM television that the site would remain close until safety could be assured.

Only Our Lady of Lourdes Basilica, a gothic church above the grotto where a French girl said she had a vision of the Virgin Mary in 1858, was kept open.

"A vision of the apocalypse in the St Bernadette Church, where the big movable partition is threatening to fall," one blogger wrote on a website. "The water has risen above the stairs of the choir.

Diocesen spokesman Mathias Terrier said the waters had reached a depth of 1.5 metres (5ft) in the grotto.

Flash floods hit Lourdes in 2011, leading to the shrine being shut down and damage estimated at hundreds of thousands of euros.