Tracker mortgage customers will see interest rates rise as early as April 13 following the European Central Bank’s decision to increase the base rate by 0.25%.

Around 350,000 of the 790,000 mortgagees are on tracker with another 250,000 on standard variable who will also see their monthly payments rise on the back of the ECB decision.

Customers can expect an increase of €15 for every €100,000 borrowed with four or five interest rates – all of a quarter per cent – expected in the next 18 months.

That means a homeowner with a mortgage of €300,000 can expect their monthly payments to increase by €45 this month with another €45 a month on top in June when the rates are expected to rise again. If there are five interest rate hikes by the end of 2012, mortgage payments on a €300,000 loan will increase by a total of €225.

Those on fixed rates will not face hikes but those seeking to switch to a fixed rate will now face higher rates than those advertised before the 0.25% rate increase announced by the ECB on April 7.

Bank of Ireland and its ICS subsidiary will increase their standard variable rates - ranging from 0.7 to 1.3 percentage points - from April 15. Bank of Ireland and ICS tracker rates will rise by a quarter-point from Wednesday April 13.

The Permanent TSB will increase its tracker mortgage rates by 0.25% from April 16.

And it will increase the rates for those on variable rates from May 18. There will be no changes to fixed rates.

Jonathan Byrne, the bank's head of Bank of Ireland mortgages in the Republic of Ireland, said fixed rate mortgages had become increasingly costly for the bank in recent months, and its current fixed mortgage rates were 'not sustainable'.

'While we have resisted increasing rates until now, we have no choice but to make this move to ensure we remain open for business,' he added.

National Irish Bank has said it will not be increasing its variable mortgage rate from the current 3.4% following the ECB announcement. The bank also said it would not increase fixed rates, though its ECB-linked tracker mortgages will rise in line with the 0.25-point increase.