The Foundation says some children go without essentials

The Joseph Rowntree Foundation said the number of children in Welsh low income households fell a fifth since 1999.

But it said 64 Welsh local authority wards had more than twice the national average of 21% of families on benefits.

The UK government welcomed the report and said it was "redoubling" efforts to meet poverty targets.

In Wales, the number of children in low-income households fell from 34% to 27% between 1999 and 2005.

But the foundation said child poverty was still causing "unacceptable suffering".

The local authorities with the some of the highest percentages of families on benefits include Bettws, Bridgend, at 52.2%, Butetown, Cardiff, at 58.3% and Tylorstown in Rhondda Cynon Taff at 55.4%.

People who grow up in poverty are increasingly likely to be poor as adults Donald Hirsch, report author

The foundation said the wards figures did not count all people who were poor, but was a good indicator of how bad poverty was in different areas.

Lord Best, the director of the foundation, said child poverty caused "unacceptable suffering".

"For some poverty means going without essentials like warm clothing and a proper diet," he said.

"For others it means not being able to participate in activities that friends take for granted.

"If we all decide to share even a small amount of future increases in our incomes with those who have the least, ending child poverty remains an achievable goal."

'Widespread hardship'

The report's author, Donald Hirsch, said to end child poverty a "strong commitment" was needed over a long period.

He said: "People who grow up in poverty are increasingly likely to be poor as adults.

"This causes widespread hardship for individuals, and carries costs for all of society.

"A big investment to wipe out child poverty once and for all will bring benefits for generations to come," he added.

A Department for Work and Pensions spokeswoman welcomed the report for highlighting "significant inroads" into the problem.

But she said the UK government but the Department recognised that there was still more to do to meet its targets.

An independent expert had been appointed to advise on maximising the impact of the government's policies, she added.