Some 400,000 home owners on tracker rate mortgages will see savings on the monthly payments from August along with Ulster Bank customers with variable rate mortgages.

Ulster Bank is the only bank so far to pass on the ECB interest rate cut to customers with variable mortgage rates.

On Thursday, the ECB trimmed the 1% interest rate to a historic low of 0.75% and this cut will automatically be passed on to anyone on a tracker mortgage.

The 0.25% cut will mean a saving of around €15 a month per €100,000 borrowed.

AIB said it will not change its standard variable mortgage rate despite the ECB's rate decision.

Bank of Ireland, Permanent TSB and KBC Bank Ireland have said they are keeping their variable rates under review.

''AIB's standard variable mortgage rates will remain unchanged, while rates will remain under review at EBS,'' the bank said in a statement.

AIB said that as one of the country's ''pillar banks'', it has a fundamental role to play in the mortgage market here but said it must do so at a sustainable economic return. It said that at current pricing levels, its mortgage portfolio - including its standard variable rate portfolio - remains loss making.

"We are working hard to return AIB to a sustainable footing so that we can ensure we deliver a return to Irish taxpayers on their investment in the bank,'' commented AIB's chief executive David Duffy.

''As part of this, the capital injected by the State should be utilised to support customers in genuine difficulty. Our products need to be priced above our cost of funding to avoid generating further losses for our shareholders. We are fully aware of the difficulties facing some of our mortgage customers and we are committed to taking all economically feasible steps to help them,'' he added.

Meanwhile, Bank of Ireland said it will continue to keep its interest rates - other than their tracker products - under on-going review, while also referring to its continuing elevated cost of funding.

However, both Bank of Ireland and AIB's tracker rate customers will see their mortgage rates reduced after the ECB cut today.

A spokesman for KBC Bank Ireland said it would pass on the ECB rate cut to its trackers customers. He added that the bank is analysing the situation regarding standard variable rates and will make a decision in due course.

Permanent TSB said the ECB rate cut would be passed on to its tracker customers while it will make a statement on its standard variable rates in the coming days.