Los Angeles - The half-sister of US President Barack Obama is to pen a children's book based on stories told by their late mother, according to an announcement Friday by children's book publisher Candlewick Press.

The book by Maya Soetoro-Ng will be called Ladder to the Moon and will pay "homage to her mother's tradition of storytelling," and her commitment to service, the publisher said.

The book is also inspired by her four-year-old daughter.

"What lessons, the author wonders, might her daughter have learned from her grandmother had the two ever met?" the publisher said in the release. No date was given for release of the book.

Obama's mother Ann Dunham gave birth to Soetoro-Ng in 1970, nine years after the US president was born. The half-siblings have different fathers.

Dunham's death at age 52 in 1995 from cancer deeply affected Obama, who has made health insurance access for all Americans a keystone of his administration. Obama has often said that his mother spent her final months "more worried about paying her medical bills than getting well."

Seotoro-Ng is a teacher at an all-girls school in Hawaii. (dpa)