Clydesdale Bank has denied reports in the Australian press that it sacked staff involved in the falsifying of customer records.

But it says some staff were "removed from their posts", and some management bonuses were affected.

The doctoring of files submitted to the financial ombudsman was a key factor behind the £20.7million fine levied on the bank this week by the Financial Conduct Authority, three times the biggest previous fine relating to PPI complaints mishandling.

The regulator accepted the bank's claim that neither senior management, nor the "PPI leadership team", were aware of the malpractice.

Australian media reported yesterday that staff had been sacked and managers punished, after Andrew Thorburn, chief executive of National Australia Bank which owns the Clydesdale, said individuals had been "removed". He added: "But it also went further because management were accountable, even if they weren't responsible. Some incentive outcomes were zero."

A Clydesdale source said the episode had impacted on bonuses, which had been zero in 2012 and reduced in 2013. He added: "The group has a clear policy of not paying bonuses for underperformance."

Debbie Crosbie, acting chief executive, said: "While we can't discuss specific individuals, appropriate disciplinary action has been taken and remains an area that we will continue to actively review. We take full accountability for our actions and for putting this right for customers."

It emerged yesterday that the process of reviewing over 100,000 claims, which The Herald predicted last November, will take up to 18 months to complete.

The bank spokesman said: "It means 10,000 cases are being reviewed every month, they are quite complex and in some cases go back beyond 2000, that is a mammoth exercise and we are committed to doing it properly."

Mr Thorburn said the outcome was "disappointing" but would not delay the planned stock market flotation of Clydesdale and Yorkshire banks.