Rents grew at a rate of 7.6% nationally in the second quarter of 2018, particularly in and around urban centres.
The figures are contained in the latest rent index from the Residential Tenancies Board.
On a quarter-on-quarter basis, rental price inflation increased 3.4% in Q2 between April and June of this year.
That is up from 2.7% over the same period a year ago.
The report shows the standardised national average rent was €1,094 a month over the second quarter of this year, which was an increase of €77 year-on-year.
The report is based on more than 18,700 new and renewed tenancies between in Q2 April and June this year.
It showed that the standardised average rent in Dublin was €1,587, while in the Greater Dublin Area (Wicklow, Kildare, Meath) it was €1,118, and outside the Greater Dublin Area was €817.
The report contains new data, for the first time, on rental trends in existing and new tenancies along with analysis on trends in the composition of the market.
The data on existing tenancies shows the year-on-year growth by 4.9% compared to 8.4% in new tenancies.
New market insights show the share of tenancies across the country with Dublin and the Greater Dublin Area accounting for more than half of all tenancy agreements.
The new analyses also show that in terms of the number of occupants, one or two occupants were in the majority of properties.
Director of the Residential Tenancies Board Rosalind Carroll said a lack of rent transparency remained an issue and the RTB was working with Minister for Housing Eoghan Murphy to have a rent register established.
Speaking on RTÉ's Morning Ireland, Ms Carroll said that the RTB was seeking to have increased powers so it could provide greater assistance to tenants.
She said: "The transparency is an issue. So what we're doing at the moment is working with the minister and the department officials to try and get legislation through that will bring that transparency - a rent register.
"We're also going to get new powers that, instead of waiting for tenants to come to us, will allow us to proactively go out, investigate and sanction, where we see any contraventions in the law."
She added that the RTB was launching a renewed campaign to highlight the rules for rent pressure zones because many people were unaware of them.
Ms Carroll said many tenants believe that the increase of 4% could only apply to existing tenancies but this was not the case.
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Warning homelessness crisis will continue
Speaking on the same programme, chairperson of the housing charity Threshold, Aideen Hayden, warned that unless the upward trend in rent is addressed, the homelessness crisis will continue.
She said the latest rent index is a continuation of a worrying trend and that the vast number of homeless are in that situation because they have lost their tenancies in the private rented sector.
Commenting on the latest index, Minister Murphy said in statement: "We know that quarterly trends can be volatile, but they do continue to rise and this continues to be a challenge. People are paying too much in rent and this has to be better controlled.
"This is why I will shortly be introducing new rent protection measures in to the Dáil. I'll also continue to pursue measures to see longer leases and tenant protections when properties are sold."
Mr Murphy added: "Home sharing will be tackled in the very near future. All of these new measures will help us move closer to a more stable and more mature rental sector.
"Some positive trends are developing though and these shouldn't be ignored. Rents for existing tenants seem to be in line with Rent Pressure Zones. One in five tenancies are for longer than four years, and one in four new tenancies agreed in the last quarter was for longer than 12 months.
"All of this is pointing to greater stability for tenants but there is still a way to go."
SF in call for emergency rent freeze
Sinn Féin has called for emergency rent freezes and tax relief to address rising rent costs.
During Leaders’ Questions in the Dáil, the party's Finance spokesman Pearse Doherty said the situation was now "out of control".
He also said there was a clear emergence of a two-tier market, with new tenancies facing higher rents because some landlords were re-letting properties following claims of refurbishment in an attempt to circumvent rent pressure zone rules.
"The reality is in a large number of cases landlords are using these loopholes to evict tenants and jack up rests," he said.
"It is scandalous," he added, and called on the RTB to be given further powers to deal with this by way of new legislation without delay.
Minister for Social Protection Regina Doherty said the report painted a more "nuanced picture" but she acknowledged that people were paying too much rent.
"One in five tenancies are now for longer than four years, which is obviously to be welcomed and one in four new tenancies is for more than 12 months, which is obviously showing a sign of stability for tenants. But having said that, there is a tremendous way to go," she said.
Minister Doherty said a Rent Register would be introduced between now and Christmas, which will show average rents, "street by street, town by town".
She also said new rent protection measures would be introduced in the Dáil in the coming weeks, which would give the RTB increased powers "to interact with people on a case by case basis".
Additional reporting Edel McAllister