The biggest apartment owner in Ireland has said that rents being charged to private tenants have risen by up to 15%.

Irish Residential Properties REIT (I-RES), which owns 1,566 apartments, also said that it is seeking to buy up to 650 more properties and it is achieving rental increases of 10-15% when leases are being renewed by tenants or when new tenants are moving into a property.

This means that renters will have to pay up to €150 more a month on a €1,000 monthly rent. The average monthly rent for the company increased to €1,364 per apartment in June 2015. This is up from €1,070 per apartment in June last year, a rise of 27%.

One fifth of people rent their homes across the country. I-RES chief executive David Ehrlich said the higher rent was due to a shortage of supply of apartments, but also to the group buying properties that command higher rents. The REIT has 100% occupancy in most of its properties, which are mainly in Dublin, including developments in Smithfield, the Docklands and Sandyford.

The company, which is quoted on the Irish Stock Exchange, bought 362 apartments in the first six months of this year.