Ratings agency Fitch has downgraded six Irish residential mortgage-backed securitisations (RMBS) on the back of “ongoing uncertainty surrounding the Irish mortgage market”.

According to the agency, which downgraded 10 tranches in transactions from a range of issuers including Ulster Bank, EBS Building Society and ICS Building Society, the Irish mortgage market is continuing to exhibit weakness.

This, it says, is evidenced by “an increasing trend of arrears, which are reaching double digits and having an effect on the entire Irish RMBS universe, albeit with differing levels of severity”.

The ratings agency has also revised upwards its predicted fall in Irish house prices, suggesting that prices could fall by 60 per cent from their peak value.

Moreover, default rates among mortgages included in the securitisation pools could hit 20 per cent, up from 15 per cent previously forecast.