The US-based Barbadian R&B singer arrived in Phuket last week and has posted several photos on her Instagram account, including ones with the endangered loris and elephants at an unidentified location.
Local wildlife advocates have alerted authorities to the picture of Rihanna with the slow loris, which is sometimes illegally used as a photo prop in tourist areas.
The Department of National Parks, Wildlife and Plant Conservation (DNWPC) has responded by urging residents to help identify where Rihanna was pictured holding the slow loris.
The Phuket News reported on its online edition yesterday that the picture is believed to have been taken on Bangla Road, off Patong Beach in Kathu district.
DNWPC deputy director-general Theerapat Prayurasiddhi yesterday said he would send officials to look into accusations of wildlife abuse if he receives specific information about where animals are being used as photo props.
"Phuket is big. We need more information before we can act," he said.
Mr Theerapat added that some zoos had obtained a licence to possess wild animals for tourist entertainment.
"If [these photos were taken] at a registered zoo with legal permission to keep animals, then we can do nothing," he said.
The slow loris is a small primate with soft fur and large eyes. Its cute appearance makes it popular with tourists visiting Thailand.
All species of slow loris (Nycticebus coucang) are protected by the Convention on International Trade In Endangered Species of Wild Fauna and Flora (Cites) under Appendix I, which bans international trade for commercial purposes.
The Rihanna incident came to light shortly after the Phuket Wan tourism news website reported a group of wildlife activists were raising funds for the establishment of a loris rescue centre on the tourist island to save the cute creatures from being exploited on Bangla Road.
The fund-raising activity was part of the Loris Awareness Week last week.
Kathu district chief Veera Kerdsirimongkol said that he had ordered environmental officials and the Kathu superintendent to "urgently investigate" the issue of lorises on Bangla Road.
Mr Veera also responded to Twitter posts on Rihanna's account referring to bizarre sex shows in Phuket.
Sex shows were completely against the law, Mr Veera was quoted as saying.
"The authorities and law officials have surveyed the area to arrest and fine those involved [in staging sex shows]," he said.
"But the shows still happen."