Not-for-profit industry fund giant QSuper allegedly rorted savings by overcharging for mandatory life insurance premiums it forced on its members through a for-profit business it created in 2016, according to a new class action against the $120 billion fund.

The Federal Court case, lodged on behalf of up to 140,000 members, comes just weeks after QSuper became the first union-and-employee-backed fund to win the right to charge its members a new fee to pay for court imposed penalties and fines.