Police say they have had dozens of tips about a group of conmen and women who are gaining access to the homes of elderly people by saying they are carrying out blood tests.

So far the gang is believed to have struck in Eindhoven, Utrecht, Delft, Ouderkerk aan de Amstel, Amsterdam and Goirle.

Last week, a 90-year-old Eindhoven man lost a large sum of money after thieves talked their way into his home saying they were testing people’s blood as part of an anti-flu campaign.

They stole more than €4,000 from his bank account after cloning his bank card.

The case was highlighted on a television crime show on Tuesday night.