Cardinal Rainer Maria Woelki, who stood in the boat outside Cologne Cathedral on Thursday, called for compassion for migrants and refugees.

Hundreds of people witnessed the liturgy.

The boat had been formerly used to transport refugees across the Mediterranean.

Authorities in Malta reportedly recovered the seven-metre-long boat used by the cardinal.

It was then transported to Cologne by Maltese church officials.

Cardinal Woelki, who has advocated or migrants and refugees for years, said refugees were people with hopes and dreams just like anyone else.

"In this boat, people young and old, women and children, were smuggled over the Mediterranean," Cardinal Woelki said.

"To see those in need and help them is the task the Lord has given to us as Christians."

On the same day Cardinal Woelki spoke, at least 20 people drowned when their boat sank north of Libya.

The day before, a trawler with hundreds of people on board capsized as an Italian navy boat arrived, killing at least five people.

Cardinal Woekl lamented such deaths, saying it is now God alone who "knows their hopes, their pain, their dreams, their sadness, their families and their life stories".

"Whoever lets people drown, lets God drown - every day, thousands of times," he said.

"Whoever tortures people to death in camps, tortures God to death - thousands and thousands of times."

Cologne has been the site of tensions surrounding migration after women were assaulted en masse, allegedly by refugees, on December 31 last year.

Some 700 refugees are believed to have drowned in the Mediterranean in recent days.

Sources

• Sydney Morning Herald
• The Independent
• Image: Sydney Morning Herald