The first national index showing the rental rates being paid has shown that apartment rents in Dublin fell by 3.9 per cent in the first quarter of 2013.

The Private Residential Tenancies Board (PRTB) also launched a new database, today, which much like the recent Residential Property Price Register, allows people to check the average amount of rent being paid in different types of dwellings in a neighbourhood.

The PRTB index is based on over 277,000 tenancies throughout the State and goes back to 2007. Unlike other reports, this one provides data on real rent levels provided by landlords who have to register with the statutory agency rather than those advertised.

Nationally rents increased by 2 per cent in the past year to €785 in the first quarter of 2013 (from €770 in the first quarter of 2012 , the report shows. However more recent trends are weaker with just 0.3 per cent growth nationally in first quarter of this year compared with the last quarter of 2012.

The report found increasing rental prices for houses across the State but weakening rents for apartments in the capital. A weakening of Dublin apartment rents (by 3.9 per cent to €964 in the first quarter of 2013 compared with the last quarter of 2012) was behind the 1.9 per cent fall in the capital’s overall rental prices, the report found. House rental income in the capital grew marginally by 0.3 per cent during the period, it found.

Rental income patterns were different outside the capital where rents grew by 1.7 per cent in the first quarter of 2013 compared to the final quarter of 2012. Apartment rents outside Dublin grew by 3.5 per cent in the period while house rents increased by 0.7 per cent.

The report compares the rental index to the CSO house price index and finds that house prices started to decline sooner than rents while the fall was greater (50 per cent in house prices since 2007 compared with 22 per cent in rents). It finds that while asking rents rose in recent Daft.ie reports the actual rents received moderately declined.

The online database will take the "speculation and surmise out of renting," PRTB director Anne Marie Caulfield said.

The tool breaks down average rents by area, dwelling type and number of bedrooms. For example it shows that the cheapest area for one bedroom apartments in the capital is Phibsboro, Dublin 7 where the average is at € 672 per month while the most expensive area, Wellington Dublin 6W, is at an average of € 1174 per month.

PRTB chairwoman Catriona Walsh noted that renting was no longera "transient option" making it "more important than ever before" to have accurate and up-to-date information.

Bob Jordan of Threshold said the database would be a valuable for tenants to negotiate during rent reviews. However it was "only as good as the number of landlords registered" he said. PRTB director Anne Marie Caulfield said the organisation had about 84 per cent of landlords registered and was making efforts to register more of them.

The rent report and rent index will be published each qurater and were produced in association with the Economic and Social Research Institute (ESRI). The report and database is available on prtb.ie.