The archbishop of Cologne has celebrated Mass in one of the cities hardest hit by devastating floods in western Germany.

Cardinal Rainer Maria Woelki led a service in Erftstadt, a small city with 50,000 inhabitants, on July 18.

"We beg the Lord for his mercy. May God help us and may God help us to help each other," said Cardinal Woelki, who returned from his vacation to reach out to people in his diocese.

The archbishop thanked emergency responders in the disaster area.

More than 150 people died when heavy rain turned minor rivers into devastating torrents in the region. Houses, cars and even parts of a motorway were torn away by the floods.

When the water hit Erftstadt, the Catholic Church was among the first responders.