Bo, a local party chief known for his charismatic personality and his crackdown on crime, once appeared headed to the top of China's Communist Party, The New York Times reported Wednesday.
China's official Xinhua news agency said Bo is suspected of involvement in serious discipline violations.
Gu Kailai, Bo's wife, has been detained along with a family servant on suspicion of having killed British businessman Neil Heywood in Chongqing last November.
Xinhua said Heywood and Gu had come into "conflict over economic interests."
Former Chongqing Municipal Police Chief Wang Lijun, Bo's former right-hand man, alleges Heywood was poisoned on Gu's orders. Heywood's body was found in a Chongqing hotel room Nov. 15. Police initially said he died of heavy drinking but his body was cremated before an autopsy could be performed, the Times said.
Bo was removed as the Chongqing party chief last month and he is thought to be held under guard in Beijing, the newspaper said.