Ulster Bank is to raise its standard variable mortgage rate by 0.6% from 1 July.
In a statement, Ulster Bank said that it had taken the decision following a review.
The rate change, from 4.35% to 4.95%, is being communicated directly to customers and will also be advertised in national press.
The increase means that customers with a €100,000 mortgage over 20 years will see their monthly payments increase by over €30, from €624.58 to €657.20.
The increase was described as 'unwelcome but hardly surprising given that we're in an upward rate cycle that is likely to continue for the foreseeable future,' by Rachel Doyle, director of the Professional Insurance Brokers Association.
Ms Doyle said 2011 and 2012 are going to be very difficult years for mortgage holders.
'The upward rate cycle is happening at a time when people are already under severe pressure with higher taxes and many with reduced incomes.'