He is a director and shareholder of MalaMala, for which the government paid more than R1bn.
It was unclear how much he stood to gain.
The department of rural development and land reform decided at the end of last year to pay R71 000 per hectare for the more than 13 000 hectares.
The game reserve is next to the Kruger National Park.
Mabunda confirmed he was a shareholder and director of MalaMala, but ignored enquiries about his role in land reform.
"My directorship and shareholding were approved in 2009 in writing by the SANParks board and the minister (of environmental affairs)," he said in an sms to Rapport.
According to the newspaper the SANParks board took Mabunda to task over an apparent conflict of interest in the matter.
SANParks subsequently announced in a statement that Mabunda's career at SANParks was ending this month.
It said his departure was not related to the alleged conflict of interest.
Both the EFF and Freedom Front Plus had criticised the claim. The FF Plus' Pieter Groenewald said it was improper that someone, who had earlier been involved in land reform was now benefiting from a land claim.