"I am extremely pleased to accept this responsibility," Bachchan said.

"I hope that by adding my voice to the cause of children it will make a difference in the lives of boys and girls here at home and across the region," he added.

Bachchan will speak on issues critical to the lives of children such as HIV/AIDS, polio eradication and the need for all girls to have an opportunity to go to school, the statement said.

"Bachchan's tremendous appeal to young people makes him an ideal goodwill ambassador. When he speaks, people from all walks of life, from the youngest to oldest, listen carefully," said Maria Calivis, Unicef representative in India.

"Our hope is to leverage Bachchan's powerful connections with the people of India to make a difference in children's lives as he has already done for polio."

Bachchan, who recently turned 61, shot to stardom playing angry young men in the 1970s, a time of political turmoil in India.

With his tall lean looks, he has since become the undisputed king of Bollywood, starting in more than 100 films.