Johannesburg  - A human rights group in Malawi, where US popstar Madonna is trying to adopt a sibling for her three-year-old adoptive son David Banda, has warned the government to grant her no special favours.

The 50-year-old star, whose 2006 adoption of Banda from an orphanage in Malawi was dogged by controversy, is expected to return to the country on Saturday with her family, Undule Mwaksungula, spokesman for Malawi's Human Rights Consultative Committee, said.

Madonna has already lodged an application through her local lawyer to adopt a second child, government has confirmed.

British tabloid The Sun claimed Friday that Madonna's heart was set on a four-year-old girl called Mercy James, whom she met in an orphanage in 2007.

"We believe if she (is) going to adopt a second child we must make sure Madonna follows the laws of Malawi, although the (adoption) laws are weak," Mwaksungula said.

While the HRCC had nothing against Madonna, the committee felt she was "using her money, actually, to influence the process and to manipulate the weak laws in the country," he added.

The Malawian government in October 2006 bypassed its own laws banning adoptions by non-residents in granting Madonna and her then- husband Guy Richie custody of David.

Banda, then 13 months, was given up for adoption by his father on the death of the boy's mother.

The adoption was confirmed by Malawi's courts last year.

The number of orphans in Malawi is estimated to be in the hundreds of thousands, in a population of 11 million. Many have lost one or both parents to HIV/AIDS and have themselves contracted the virus through mother-to-child transmission.

Half of all citizens of the landlocked country live below the poverty line, leading some parents like Banda to feel their children are better off in an orphanage. dpa cb jbl