WASHINGTON (AFP) - First Lady Michelle Obama took her campaign against childhood obesity to a new level on Thursday with a US$150 million (S$186 million) programme to encourage more physical activity in American schools.

Let's Move! Active Schools builds upon the Let's Move! initiative that the mother-of-two and wife of Mr Barack Obama unveiled three years ago during the president's first term in the White House.

"Only one in three of our kids is active every day," said the first lady in Chicago, the Obama family's hometown. "That's not just bad for their bodies. It's also bad for their minds, because being less active can actually hurt kids' academic performance."

Funded by a public-private partnership, Let's Move! Active Schools aims within five years to get 50,000 schools across the United States (US) to provide at least one hour of physical activity per day to their youngsters.

Excessive weight is a major public health issue in the US, where two in three adults - and one in three children - are either overweight or obese, officials say.