Bollywood legend Amitabh Bachchan has been appointed goodwill ambassador of the United Nations Children's Fund (UNICEF).

Bachchan will be focusing on polio eradication and educating the people on HIV/AIDS, the UNICEF said in a statement Saturday.

In a signing ceremony at the UNICEF headquarters in New York, Bachchan agreed to make public appearances and field visits on behalf of children for the next two years.

A 12-day retrospective of Bachchan's work is running in New York.

"Amitabh has the star power to illuminate the lives of millions of children who are living in dire circumstances," UNICEF executive director Carol Bellamy said.

"We look forward to a long collaboration with him, and we feel honored to have him as part of the UNICEF family."

Bachchan has previously supported the UNICEF during a polio outbreak in northern India by making award-winning and effective television and radio advertisements that had him urging parents to get children inoculated against the crippling disease, the UNICEF said.

After the tsunami disaster Dec 26 last year, Bachchan made a public service announcement asking the people to protect children, particularly in times of crisis, the UNICEF said.