Investors in the collapsed Connaught Income Fund have accused the UK financial regulator of “lying” about the £104m loss they suffered in an attempt to avoid paying them any more compensation.

The Connaught Action Group, which represents about 2,000 investors in the fund that went bust in 2012, on Monday said the Financial Conduct Authority was deliberately understating how much money they are owed in an attempt to draw a line under the scandal.

It is demanding a “correction” to recent FCA statements, plus the return of an outstanding £24m, and redress for lost income, consequential losses and opportunity costs.

If the FCA does not agree, the group has said it would bring a formal complaint against the regulator’s new chief executive Nikhil Rathi, as well as its chair Charles Randell.

Last week, an independent review into the Connaught collapse, by barrister Raj Parker, found that “regulation of the relevant entities and individuals connected to the fund was not appropriate or effective”. It concluded the FCA “could have acted in a more effective way to protect investors in the fund”.

Investors believed this finding would result in a new compensation scheme being set up to consider the total investor loss of £104m, as identified in the Connaught liquidator’s report. A similar scheme for investors in failed mini-bond issuer London Capital and Finance was announced on the same day the Connaught review was published.

However, the FCA responded to the Parker review by saying the fund had “aggregate principal losses estimated at £79m” — and stating that “investors have received over £80m” from an earlier redress scheme.

According to a person familiar with the FCA calculation, the £79m figure reflects the aim of the redress scheme established by the fund’s original operator, Capita Financial Managers. This was designed to give back investors their capital less any amounts they had received in interest or dividends.

But the Connaught Action Group has consistently argued that “principal” capital lost was the £104m listed in the fund’s books, and any additional income owed on it cannot be deducted from the total.

It accused the regulator of misleading the public by implying that investors had received full repayment. “The FCA is lying when it says Connaught investors lost only £79m and have therefore been compensated in full,” said the group’s leader, Mark Bishop.

“You cannot knock the income off and claim it this was part of our original capital,” he explained. “It was paid out as income and taxed as income.”

In addition to the unrecovered £24m of capital, the group is demanding compensation for the interest they lost on their money when Connaught went bust, plus the opportunity cost of not being able to access their capital or invest it elsewhere.

The FCA denied it was misleading investors and said the sums due to them had been explained in detail already.

“We have made clear our approach to calculating the redress payment from Capita,” a spokesperson said, noting that the aim of the payment was to return to the fund’s investors their capital investments less any amounts which they have received in interest and by way of redemptions, distributions, payments or dividends. An interest rate of 0.52 per cent was also applied to the payments, the spokesperson added.