Annual inflation fell to 4 per cent last month but consumer prices increased by 0.3 per cent in September.
In its latest figures today, the Central Statistics Office said this compares to an increase of 0.8 per cent in September of last year and that as a result the annual rate of inflation dropped to 4 per cent, down from 4.5 per cent in August.
Fine Gael's Richard Bruton
The highest monthly prices changes were increases in clothing and footwear (5.3 per cent), while housing and energy costs were up by 2.9 per cent in September.
The increases were partially offset by a drop of 2.8 per cent in transport costs.
The greatest rises in inflation in the year to September were housing and energy costs, which jumped by some 18.6 per cent. Education costs were up by 4.7 per cent, while health costs rose by 4.2 per cent.
There was a slight drop of 1.9 per cent in clothing and footwear prices, while furnishing and household equipment also fell by 1 per cent.
The annual rate of inflation for services was 7.5 per cent in September, while the price of goods showed no change in the year.
Fine Gael said the latest inflation figures had "exposed the Government as the biggest cause of Ireland's worsening inflation rate".
The party's deputy leader and finance spokesman Richard Bruton said Irish inflation was 2.7 per cent higher than the Eurozone average, but was 0.6 per cent lower than the Eurozone in areas where the Government has no role.
"New inflation figures are remarkable for showing that the Government is the single biggest cause of rising prices. Prices controlled by the Government are now growing at more than four times the rate of increase in prices where Government influence is absent," Mr Bruton said.
"By contrast, governments in other European countries are managing to keep these prices down."
Mr Bruton claimed the further impact of proposed gas and electricity price increases will shove overall Government prices up by another ten points to 61.5 per cent.
"Not only has the Government been increasing its own prices way ahead of all others but in the past five years it has also increased both of rates VAT. Ireland now has the highest VAT burden in the European Community.
"The Government's claim to be a low-tax administration is an illusion. The OECD has today confirmed that Ireland is alone among the OECD countries where the tax-take as a portion of income is increasing. However, even more damaging in the long term is the Irish Government's role in increasing the cost of living and doing business by stealth. This pattern is unsustainable."