American pop queen Madonna broke ground Monday on a girls academy she is building in Malawi, billed as a "gift" to the country where she has adopted two children.

The 51-year-old star cut a cake, planted a tree and turned the sod alongside her eldest daughter Lourdes, 13, at a colourful ceremony attended by about 500 locals on the outskirts of Malawi's administrative capital Lilongwe.

According to a brochure for the Raising Malawi Girls Academy, the school will be a - leadership institution to prepare future women leaders - with 500 boarders including two impoverished girls from the country's 28 districts.

It will - focus on mathematics and science which traditionally have failed in Malawi and elsewhere - the brochure said.

Madonna's school is modelled on a similar academy built by US television talk show host Oprah Winfrey.

In 2006, the chart-topping musician adopted a baby boy, David Banda, who is now three-years-old. She returned to Malawi this year to adopt a girl, Mercy James.

Madonna is also funding several charities in the small southern African country, including homes for children with AIDS.

Construction of the academy will take two years.