Mauritius authorities have arrested the aide to former Madagascan president Andry Rajoelina on suspicion of money laundering, an official at Mauritius' Financial Crimes Commission said on Friday.

Maminiaina Ravatomanga, who fled to Mauritius after Rajoelina also left the country following youth-led protests, was in the custody of the police and officials of the Financial Crimes Commission in a private clinic where he had gone to seek treatment in Port Louis, a commission spokesperson said.

The spokesperson, who did not wish to be named, said Ravatomanga's arrest was related to the laundering of 7.3 billion Mauritian rupees ($163 million) using assets in Mauritius.

"The FCC has reasonable grounds to believe that ... Ravatomanga, while being involved in the management of several entities in Mauritius, was in possession of property suspected to represent the proceeds of criminal activity," the spokesperson said.

Ravatomanga's lawyer, Siddartha Hawaldar, confirmed he was under arrest in the clinic, but did not comment on the accusations against him.

Madagascar's new leader Colonel Michael Randrianirina was sworn in as president last Friday and on Monday named businessman and consultant Herintsalama Rajaonarivelo as the island nation's new prime minister.

Ex-leader Rajoelina, whom lawmakers impeached after he fled abroad 12 days ago, has condemned the takeover and refused to step down while in exile, despite defections in the security forces and the High Constitutional Court ratifying the takeover within hours of it happening.