The education gap between children from disadvantaged backgrounds and those of wealthier families is getting worse, federal Education Minister Jason Clare says.
Recent NAPLAN data shows a difference of up to two years when comparing test results for reading from eight-year-olds of different backgrounds.
The disparity increased to about five years by the time a child reached year nine.
Mr Clare said the effect ricocheted through generations.
"I have said a number of times, I don't want us to be a country where your chances in life depend on who your parents are, where you live or the colour of your skin," he said on Thursday.
"But here we are."
Overall, primary school reading test results were better than in 2006, but levels of achievement at secondary school remained the same.
"The big gains in primary school aren't leading to big gains in high school," Mr Clare said.
"What I am even more worried about is this - the gap between children from poor families and children from wealthy families is getting bigger."
The minister said children from disadvantaged backgrounds were less likely to attend preschool, finish high school or study at university and he would keep that in mind when allocating federal education funding.
States and territories are set to begin a fresh round of negotiations on the national school reform agreement later this month.