High street banks are slashing credit card limits and turning away droves of borrowers in a consumer credit crackdown.

Banks hope that by tightening up lending standards they will cut the cost of servicing problem borrowers.

Half a million Barclaycard customers have seen their credit limits reduced in a continuing review by Barclays of its customers’ spending behaviour.

The bank is rejecting half of all applications for cards and is monitoring card-users closely for signs of trouble.