Image copyright Reuters Image caption Jiang used to head the China National Petroleum Corporation which is the parents company of PetroChina

The former chief of China's biggest oil firm has been sentenced to 16 years in prison for accepting bribes, state media said.

Jiang Jiemin was previously head of China National Petroleum Corporation (CNPC) and its listed firm PetroChina.

He was arrested in 2013, shortly after taking a government job.

Jiang was an ally of former security chief Zhou Yongkang, the biggest official caught in the ongoing corruption crackdown in China.

A statement from a court in Hubei province carried by local media said Jiang was found guilty of "receiving bribes, possessing large amounts of assets of unknown provenance, and abusing power as a state-owned company employee."

Media outlets said that Jiang had amassed a total of 14.8m yuan (£1.5m, $2.3m) in assets. Besides his jail sentence, authorities have confiscated assets worth 1m yuan from him, local media said.

The BBC's Celia Hatton in Beijing says he received a lesser sentence after confessing his crimes and detailing the bribes he received in exchange for approving construction projects and offering personal job promotions.

Corruption drive

Pictures of Jiang in court published online showed the visibly thinner former official listening to the verdict with an impassive face.

Jiang had risen through the ranks of state-owned CNPC, which is the parent company of PetroChina, in the late 1990s and 2000s to become chairman.

He left CNPC in April 2013 to take his highest position yet, as head of the State-owned Assets Supervision and Administration Commission - a cabinet-level position. He was arrested a few months after assuming that position.

China has been conducting widespread arrests of both low-ranking and high-ranking officials since President Xi Jinping took power in 2012.

One of its biggest hauls was Zhou, the former head of China's Ministry of Public Security, who was sentenced to life imprisonment for corruption in June.

Our correspondent says China's leaders use high-profile cases to prove they are serious about tackling government graft.

However, many suspect that the downfall of Jiang and others can also be attributed to ongoing political infighting.