LONDON - Social mobility has not improved in Britain in 30 years with bright children from poor families being overtaken by less able youngsters from rich homes by the age of seven, a report released on Thursday said.

The findings show that the academic progress of children is still overwhelmingly linked to their parents' income giving them little opportunity to close the wealth gap, said the Sutton Trust charity which commissioned the study.

"Shamefully, Britain remains stuck at the bottom of the international league tables when it comes to social mobility," said Peter Lampl, the trust's chairman.

"It is appalling that young people's life chances are still so tied to the fortunes of their parents, and that this situation has not improved over the last three decades."

The report said that children from poor households who are in the brightest group at the age of three slip back in developmental tests by the age of five, and are likely to be overtaken by those from affluent backgrounds by seven.

It found that 44 percent of those from the richest 20 percent of households attained a university degree compared to just 10 percent from the poorest 20 percent of homes.

The survey said there had been a sharp decline in intergenerational income mobility -- the ability of children to earn more than their parents -- for those born in 1970 compared with those born in 1958.

While that decline had not continued between 1970 and 2000, the situation had not significantly improved, according to the study by researchers from the London School of Economics and the University of Surrey.

"We cannot find any evidence that the sharp drop in mobility observed for children growing up in the 1970s and the 1980s has continued. But nor can we find evidence that mobility has improved," said Dr Jo Blanden, one of the report's authors.

Beverley Hughes, the Minister for Children, Young People and Family, said it was encouraging that the "previous decline" had stabilised.

She said the government had made closing the wealth gap a top priority, pointing to the 10-year children's plan unveiled on Tuesday with measures to improve education and help those in deprived areas.

"As we look to the future we hope to see more evidence of our reforms making a real difference to people's lives, and improving the economic and social prospects for people born into more disadvantaged circumstances," she said.

However, opposition parties condemned the findings, saying it showed the government's educational reforms had failed.

"Instead of the gimmicks and further reviews that were announced earlier this week, ministers need to urgently tackle the inequality at the heart of our education system," said David Laws, the Liberal Democrat children's spokesman.