The ‘fraudster families’ often hire rogue financial experts to run the large-scale scams on their behalf.

Victims of these scams lost an average of £91,000 each to fraudsters in 2017 but some people have lost much more.

They reported receiving cold-calls, offers of free pension reviews and promises that they would get high rates of return – which are all key warning signs of scams.

Intelligence gathered by members of the multi-agency Project Bloom group, which was set up to tackle pension scams, indicates that a number of ‘fraudster families’are targeting pension holders.

Criminal investigations involving regulators, government agencies and police forces are currently ongoing into a number of these gangs.

A number of individuals linked to the scams have been suspended or banned from being trustees and companies used for scams have been shut down.

Nicola Parish, The Pension Regulator’s Executive Director of Frontline Regulation, said: “[Pension] trustees and administrators play a key role in preventing members from falling victim to scams by identifying suspicious requests early.

“The better they are at spotting the signs of a scam, the quicker members can be warned and we can investigate.

“Working together we can target those trying to plunder people’s pension pots and bring them to justice.”

A ban on pension cold calling came into force earlier this month. Firms that break the rules could face penalties of up to £500,000.