The chair of parliament’s work and pensions committee has called for a law change following reports that Monarch’s owners will get a bumper payout while those in the pension plan lose out.

Labour MP Frank Field told the Guardian of his concern that private equity Greybull Capital – which bought the now failed airline in 2014 – could avoid losing money while Monarch’s pension fund is owed £7.5 million and could be left with nothing.

As part of the Greybull takeover, the pension scheme – which had a deficit of about £158m at the time – was separated from the company.

Pension regulators agreed to the move as they were sure the airline would have gone bust within 12 months, the Guardian reports.

Field, whose committee investigated the pensions scandal following the collapse of BHS, has written to the chief executive of the Pension Protection Fund (PPF), Alan Rubenstein, questioning the status of Monarch’s fund.

He wants to know if the PPF, which rescues pension funds attached to failed companies, has received any payments yet from Monarch relating to the £7.5m, and where the pension fund sits in the order of creditor preference.

Responding to the report, Field said: “How can it be that, once again, mega-rich individuals could walk away from a collapsed company with a bumper profit while ordinary people pick up the bill?

“This massively supports the case for the law to change, to robustly protect pension schemes.”

Greybull said it hoped the PPF loan note would be paid back and that its original financing had been agreed by industry watchdog, the CAA.

The company said it had not taken out loan repayments, dividends or interest in the last three years and in a statement to the Guardian, said: “Monarch’s demise cannot be reasonably attributed to the actions of Greybull.”

Malcolm Weir, director of restructuring and insolvency at the PPF, said that, without the PPF’s protection in 2014 when the airline was restructured, Monarch pension scheme members would have left with nothing.

He said: “The expected recovery for the pension scheme if Monarch had gone bust in November 2014 was £0.

“The £30m in cash secured for the scheme by the restructuring of Monarch was much more than the scheme would have otherwise received. The restructuring met the PPF’s published tests.”