A major new strategy is urgently needed to combat the effects of poverty on educational performance, according to a leading academic and former adviser to the Assembly government.
David Egan, professor of education at the University of Wales Institute, Cardiff, said the "strong and enduring" link between poverty and low attainment is one of the major weaknesses of Wales's education system and a "blight on the nation".
The National Assembly's children and young people committee has launched a follow-up to its 2008 inquiry into the Assembly government's policies to tackle child poverty through education.
The government's child poverty strategy and delivery plan is due to be published soon.
Giving evidence to the cross-party committee last week, Professor Egan said the strategy must put an end to Wales's high-achieving but low-equity education system if it is to succeed.
While countries like Finland, Canada and Korea have overcome the problem, and others like England are making good progress, Wales is still struggling, he said.
Although achievement gaps exist in all schools, they are widest in those with high concentrations of pupils entitled to free school meals.
Professor Egan said: "Socioeconomic class in Wales is a dowry leading to low educational performance. In the vast majority of cases, the more of them that bring that dowry with them to their place of education, the worse they and it will do."
An evaluation is currently taking place on the outcomes of the four-year RAISE (Raising Attainment and Individual Standards in Education) programme, which channelled millions of pounds to the most disadvantaged schools to help them implement their own approved strategies.
But Professor Egan said that although there were some excellent examples of success, Raise suffered from "weak implementation" and "missed opportunities".
He said that any strategy to improve educational fairness should be universal and recognise that the influence of socioeconomic status is three times more powerful than other factors like gender and ethnicity.
It should have an emphasis on early years education with appropriate intervention strategies, a strong focus on supporting disadvantaged students aged eight to 14, and an engaging 14-16 curriculum, he added.
According to Professor Egan, the key to success lies in recruiting and retaining the best teachers in the most challenging schools, and developing high-quality leaders who can change the low-performing school culture by raising expectations.
In its evidence to the committee, the End Child Poverty Network Cymru also called for a strategic national direction as a matter of urgency.
It said that while initiatives like the school effectiveness framework and the 14-19 learning pathways could improve educational outcomes - depending on the way they are delivered and implemented - schools cannot do it alone.
Statistics from the Department for Work and Pensions last year showed the number of children living in poverty in Wales was around 200,000 - a third of the child population.
In his evidence to the committee, deputy minister for children Huw Lewis said he hoped the new strategy would "wholly and completely" address prior criticisms of the lack of strategic co-ordination from the Assembly government.
He said: "We are all well aware of, and are well versed in, the statistics relating to educational attainment, which are stark and frightening. We should not take our eye off the ball when it comes to the impact of poverty and deprivation on educational attainment."