The Minister for Social Affairs said he is committed to taking "swift and decisive action" on child poverty.
Mr Brennan said serious consideration is now being given to the introduction of a second tier of supports - in addition to the Child Benefit and other support entitlements - aimed at addressing those children most at risk.
The Minister's comments follow the publication by the CSO of figures that reveal nearly 15 per cent of young people have high levels of consistent poverty.
"Linked to this are the vulnerable circumstances of many lone parents. The existing support systems will be scrutinised over the coming months and changes considered that more adequately reflect the needs of this group, and society in general, in a 21st century Ireland."
Mr Brennan said efforts must now be redoubled to eradicate poverty and social exclusion from society.
He said the CSO survey's findings would be a valued contribution to the comprehensive research already undertaken into income, living standards and the extent of poverty in Ireland.
"We must take heed of the message that this survey delivers which is that, despite the extremely positive and targeted action taken by Government and the record levels of spending on social welfare, some people continue to be vulnerable and to struggle on the margins of society," the Minister said.
"Whatever about the findings, and the debate over the different methodology used, we must not lose sight of the fact that the rising tide of economic progress has not, as we would all have desired, raised all boats and that we must all redouble our efforts to work to eradicate poverty and social exclusion from our society."
Mr Brennan said it should be noted that the Living In Ireland Survey (LIIS) undertaken by the ESRI between 1994 and 2001 had previously been the source of all data on poverty. He also noted that the methodology used for the LIIS and the new study was different.
"This survey measured consistent poverty in Ireland for individuals at 5.2 per cent
in 2001. The EU-SILC [EU Survey on Income and Living Conditions] survey was conducted in 2003. Between 2001 and 2003 spending on social welfare has increased substantially, from €7.8 billion in 2001 to €10.5 billion."
Mr Brennan said that social welfare payments had increased by 17 per cent for both the basic rate and the old age pension between 2001 and 2003, which was well ahead of the consumer price index and the rise in average industrial earnings. Child benefit had increased by some 45 per cent in the same period and between 2001 and 2005 that had risen to 65 per cent.
The Minister said that since the survey was conducted in 2003, the Government had delivered two budgets that had directed further significant additional spending to social welfare. This year, he said, his Department would spend some €12.2 billion, or almost one-in-three euro spent by the State, on social welfare. This was more than double the figure for 1997, when the Government began its first National Anti-Poverty Strategy.
But the Green Party's spokesman on social and family affairs, Mr Dan Boyle, said the survey revealed "truly shocking" facts about poverty in Ireland that were "shameful" as far as Government policies were concerned.
"These are damning facts for a Government that continues to preside over deepening and widening social division in this country," Mr Boyle said.
"The gap between the top and bottom income groups is five to one, highlighting the realities of the Government's policies for those without in our society, despite December's so-called 'socialist' budget."
The Labour Party's spokesman on social and family affairs, Mr Willie Penrose, said the survey was indicative of the gross imbalance in Government policy in favour of the better off.
Mr Penrose said that this is the latest in a litany of studies which highlight the extraordinary levels of consistent poverty among vulnerable groups such as lone parents and households with children.
"The stark reality of life for people on low incomes is the regular imposition of Government-sanctioned price increases - higher charges for a visit to a GP; huge increases in the cost of gas, telephone and electricity bills; spiralling costs in education; a 30 per cent increase in the cost of fuel in three years are among a range of stealth taxes that are obliterating the social welfare increases of recent years.
"Until such time as those on low incomes and those in vulnerable financial circumstances are supported adequately to help them to meet household bills and until the Government stops hammering families with stealth taxes and price increases, consistent poverty will remain a feature of the so-called booming economy," he added.