Research by the Sutton Trust has found that the UK lags behind Canada and Australia when it comes to the reading gap between the children of lowly and highly educated parents.
In Canada and Australia five year olds with less educated parents are already behind the children of highly educated parents by an estimated six months when they start school, whilst in America they are about a year behind.
While the study was based on parental education, the researchers said the gaps were similar for parental income.
The research also found that the attainment gaps in the US and UK are much bigger today than they were for children born 40 to 60 years ago, although these gaps have started to narrow slightly in the past decade.
The Sutton Trust said greater efforts were needed to reduce the disparity in Britain by focusing on the early years.
The foundation has called on the government to make sure that disadvantaged children have access to the best early years education by employing qualified and well-trained staff in all early settings.
Access to free child care places should be accompanied by easy access to proven parenting programmes, it said.
The foundation also said that improving the quality of classroom teaching should be the top priority to reduce the attainment gap once children were in school.
Sir Peter Lampl, founder and chairman of the Sutton Trust and chairman of the Education Endowment Foundation, said tackling the reading gap was “critical to breaking the cycle of disadvantage and reducing inequality”.
“We need to make sure that every child has access to high-quality early years education, so that rich and poor children arrive at school on a more equal footing”.
The Sutton Trust study drew on research from across the world and was conducted by Jane Waldfogel of Columbia University and the London School of Economics and Sean Reardon of Stanford University.