Madonna holds the child named Mercy, whom she hoped to adopt, in an undated photo taken in Malawi and released to Reuters April 13, 2009.?[Agencies]

(Reuters) - Madonna will formally appeal next month against a Malawian court ruling that said she could not adopt a second child from the African country, her lawyer said on Monday.

Malawi's High Court ruled this month the U.S. pop star could not adopt a four-year-old girl, named Mercy James, because she was not a resident of Malawi. The Supreme Court of Appeal will hear the case. Madonna is not expected to appear.

"I cannot disclose our grounds of appeal but I can confirm that the court will hear our appeal on the 4th of May," her lawyer Alan Chinula told Reuters. "

Malawi's government came under fire after Madonna adopted a 13-month-old child, David Banda, in 2006, with critics accusing it of giving her special treatment by skirting laws that ban non-residents from adopting children.

Rights groups accused the government of giving Madonna, a U.S. citizen, special treatment. The government had supported Madonna's attempt to adopt Mercy, saying she was a worthy mother.

An AIDS epidemic in the southern African country has orphaned more than one million children and Madonna has set up a charity for Malawian children.

"I want to provide Mercy with a home, a loving family environment and the best education and healthcare possible. And it's my hope that she, like David, will one day return to Malawi and help the people of their country," Madonna told Malawi's Nation on Sunday newspaper in an emailed response to questions.

In her ruling, High Court judge Esimie Chombo warned against celebrity adoptions, saying they could lead to child trafficking.

Madonna has entertained millions around the world with hits like "Material Girl" and "Papa Don't Preach," creating a fair amount of controversy along the way.

The star, who was divorced last year from British film director Guy Ritchie, is one of the music industry's most successful singers, with album sales of more than 200 million.