A rising star of Angela Merkel’s party who has been tipped as a future chancellor is calling for hate speech laws to be used to prosecute Muslims who refer to non-believers as infidels.

The push for a tougher approach to integration came from Jens Spahn, 37, deputy finance minister, who is on the conservative wing of the Christian Democratic Union (CDU).

With Mrs Merkel expected to win this month’s election Mr Spahn is among the next generation of CDU politicians positioning themselves to succeed her if, as many expect, she bows out near the end of a fourth term.

A gay Roman Catholic, Mr Spahn has established himself as a hardliner on immigration at a time when many in the CDU believe the party should