An Austrian cardinal who is one of the favourites to become the next Pope has warned that Europe faces its biggest threat from Islam since the 17th century.

In an astonishing speech the Roman Catholic Cardinal of Vienna, Christoph Schönborn, warned that many Muslims wanted to eradicate Christianity and conquer Europe.

He was speaking at the Holy Name of Mary festival on Sunday which dates back to 1683 when it was first held in gratitude for the victory of the Austrian Habsburg Empire over the Ottoman Turks.

The Local newspaper said the cardinal said: 'Will there be an Islamic conquest of Europe? Many Muslims want that and say: Europe is at the end.'

He asked God to have mercy on Europe and said the continent was 'in danger of forfeiting our Christian heritage'.

In a comment which is bound to be seen as an endorsement of the far-right Austrian Freedom Party Cardinal Schönborn said people were seeing their loss 'not only economically, but above all, in human and religious matters'.

The cardinal is seen as a future Pope who, at the relatively age of 60, has time on his side.

The Argentinian-born Pope Francis was only chosen in 2013 but he will be 80 later this year and may one day decide to follow his predecessor, Pope Benedict, who resigned the post due to ill health, aged 86.

Muslims still make up only 10 percent of the population in Vienna.

Europe has been threatened militarily by Islamic foes twice before.

In the eighth century the Muslim Moors invaded and conquered most of Spain and parts of southern Italy and were only stopped by defeat at the Battle of Tours in France. They were later turfed out of Iberia by the armies of El Cid.

The Battle of Vienna in 1683 was an epic clash of cultures and a major turning point historically as the Muslim Ottoman Turks never seriously tried to advance further into central or western Europe after their defeat by a joint Polish and Austrian army

But in September 1683 an army of 100,000 soldiers from the Ottoman Empire arrived at the gates of Vienna, having already conquered the Balkans and Hungary.

The Austrians, supported by the Polish-Lithuanian Commonwealth and the Holy Roman Empire, defeated the Ottomans and turned the tide of their advance.

The Austrian Freedom Party held its own event to mark the battle, which involved speeches by Vienna's Vice-Mayor Johann Gudenus and Freedom Party leader Heinz-Christian Strache, as well as historian Dr Lothar Hobelt.

Relations between Austria and Turkey have cooled recently with Austrian Foreign Minister Sebastian Kurz reacting to the coup and the mass purge which followed it by saying he wanted to stop any moves to bring Turkey closer to joining the European Union.