Irish banks are under threat of being penalised by the government if they do not speed redress for the growing number of borrowers who should have paid less on their mortgages.

The industry-wide compensation scheme concerns customers who should have been given the option of a cheaper "tracker" mortgage that follows the low European Central Bank rate or kept on a better rate years ago.

"Many lenders publicly state that they put customers first. The evidence of the examination that we have seen suggests otherwise," Central Bank Governor Philip Lane said in a statement.

It said 297 million euros (£262.47 million) had been paid in redress by mid-December. The majority of customers identified in an earlier Central Bank report in October have been compensated, it added.

The bank said the 13,600 cases included 5,800 customers formally reported as verified by lenders.

Bank of Ireland in November said it had made provisions for an additional 6,000 customers after the Central Bank identified them as having been impacted. But the Central Bank declined to say if all of the 5,800 were Bank of Ireland customers.

The remaining 7,800 have yet to be verified by lenders for inclusion in redress and compensation schemes, the Central Bank said.

The 33,700 cases include 7,100 resolved before the central bank opened its probe in 2015.

(Reporting by Conor Humphries, editing by Louise Heavens)