Boys

that she co-founded a business, Girls Will Be, which provides empowering shirts and shorts so girls can live their active lives and still feel good about what they wear.

The business was inspired, in part, by her soon-to-be-12-year-old daughter, who could never find anything she wanted to wear in the girls' department.

Unicef said the difference in time spent working amounted to 160m extra hours a day worldwide.

Two out of three girls cook and clean in the home, and almost half collect water or firewood.

They also perform more "less visible" domestic work like childcare or looking after the elderly, the report says.

It also found that the extra workload increased with time: between ages five and nine, girls spend 30% more time on chores - by 14, it rises to 50%.