Three operators in Cameroon have come under fire from anti-corruption regulators for allegedly defrauding the state of $289 million, according to Bloomberg.

Market leader MTN, France’s Orange and state-owned CamTel are accused of evading taxes, royalties and receiving illegal tax rebates in a report by the National Anti-Corruption Commission (Conac).

According to the report, released by commission chairman Dieudonne Massi Gams, the ministries of finance and post and telecommunications colluded with the operators by providing illegal tax rebates.

The issue dates back to activities between 2010 through to 2014, with the telecoms regulatory board also accused of failing to act on the alleged wrongdoings.

Conac’s Vice President, Garga Haman Adji, told Bloomberg the regulator expects that Cameroon president Paul Biya will order legal investigations over the matter to establish why “two ministries of his government can afford to grant rebates to the operators”.

MTN and Orange officials are reportedly studying the report.

According to GSMA Intelligence, South Africa’s MTN is estimated to have just under 10.5 million connections in the market as of Q4 2015. Its closest competitor is Orange with more than 8 million connections, while CamTel lags behind with 27,095 connections. Viettel’s Nexttel is the country’s third largest player with more than 3.6 million connections.