An Austrian cardinal who is one of the frontrunners to be the next pope has warned of an "Islamic conquest of Europe".

According to reports of his speech to mark the 333rd anniversary of the Battle of Vienna, Cardinal Christoph Schönborn said: "Will there be an Islamic conquest of Europe? Many Muslims want that and say: Europe is at its end."

“God have mercy on Europe and on thy people, who are in danger of forfeiting our Christian heritage,” the cardinal reportedly prayed.

He claimed that this was already being felt "not only economically, but above all, in human and religious matters".

The speech was made on Sunday at the "Holy Name of Mary" church festival, which marked the 333rd anniversary of the Battle of Vienna in 1683 in which Christian forces defeated the Ottoman Empire army.

Cardinal Schönborn, 71, is a conservative who was a former student of Pope Benedict XVI - and has even been referred to as the former pope's "spritual son".