Grandparents play a critical role in their grandchildren's lives, helping boost their development even through simple activities such as reading to them or going shopping together, an Australian study said.

The four-year government-funded study, released on Tuesday, measured children's physical, learning and cognitive development, in addition to social and emotional functioning.

It showed that children aged from 3 to 19 months had higher learning scores if they were cared for by family and friends -- including grandparents -- as well as their parents.

"This new study demonstrates just what a critical role grandparents play in the development of children," Federal Families, Housing and Community Services Minister Jenny Macklin was quoted by Australian media as saying.

"We know from this study how important it is to a child's development to ... spend as much time as possible every day reading and spending time playing with children," she said.

The "Growing up in Australia" report is the first comprehensive national study of Australian children over time, Macklin said. More than 10,000 families with children took part in the study, which started in 2004.

Miral Fahmy, Alex Richardson