The Malawian social worker assigned to assess Madonna's suitability to adopt a child from the African country has been removed from the case.
Madonna took custody of David Banda in October 2006
Penstone Kilembe was due to visit the pop star in London this week to assess toddler David Banda's progress.
But he has been replaced by welfare officer Simon Chisale after court action by the Malawian government.
It is unclear if his removal is linked to claims he obtained cash and an air ticket from Madonna without approval.
Madonna's spokeswoman said there had been "absolutely no interference" with government officials and "no use of Madonna's 'celebrity'" to speed up the adoption.
Mr Chisale is expected in London on Tuesday to carry out the assessment.
Mr Kilembe, who returned to Malawi on Monday after attending a conference in the US, said he had not heard of the move and denied any wrongdoing.
"I am not aware of these developments. I have just arrived from New York and nobody from my office has told me anything. I will be in the office tomorrow," he said.
Madonna and her husband, film director Guy Ritchie, were granted an 18-month interim custody order of David, then 13 months old, in October 2006.
His father had placed him in an orphanage after his mother died.
Critics accused Madonna of using her celebrity status to circumvent Malawian laws in adopting David, an allegation she denies.
In an affidavit presented to the court, child welfare officials said Mr Kilembe was leaving the ministry and "moving on to a new posting", but did not go into detail.
Mr Chisale, the country's chief social welfare officer, confirmed he had been appointed to replace Mr Kilembe but refused to discuss the adoption further.
Madonna's lawyer in Malawi said he was co-operating with Mr Chisale.
A further inspection has been scheduled for December, and a report is expected to be filed before the courts by February 2008.
A judge will then decide whether the Madonna and her husband are suitable adoptive parents.
Their custody order could be revoked if it is found that David was being treated differently from their other children, Lourdes, 10, and Rocco, six, or if the toddler's rights were being violated in any way.
Madonna's spokeswoman, Liz Rosenberg, said on Tuesday that the adoption was going ahead as planned.
She added: "All appropriate legal requirements are being followed, including a home visit.
"Madonna and her entire family look forward to being granted the final adoption early next year - 18 months following the original interim adoption order."