Tourism Minister Rufino Ndong Esono Nchama and former economy and finance minister Valentin Ela Maye are suspected of having links with the swindlers and receiving monthly kickbacks, it said.
The scam allegedly entailed nine fake companies which over three years won two dozen contracts for maintaining public buildings and beaches by falsifying the signature of President Teodoro Obiang Nguema Mbasogo.
"Ten billion CFA francs" ($17 million) in state funds were siphoned off, the report said.
Five individuals suspected of setting up the bogus firms are being held at the police station in the capital Malabo, TVGE said, without identifying them.
A source close to the inquiry told AFP that the number of people involved in the scam was still unclear.
Investigators will need authorization from the prime minister to interview Nchama as he is a serving minister, TVGE said.
The justice ministry, approached by AFP, declined to give details about the charges facing the five or the likely penalties they face if convicted.
E. Guinea Launches Ministers' Graft Probe
FILE: Map of Equatorial Guinea. Uploaded Jan. 6, 2014
MALABO, EQUATORIAL GUINEA - Investigators in Equatorial Guinea are probing a minister and a former minister for suspected involvement in a major scam, state television TVGE said on Friday.