Updated

A new report from a human rights group says torture, solitary confinement and coerced confessions are rife in investigations of Chinese Communist Party officials detained on suspicion of corruption.

The study by Human Rights Watch analyzes the supervision of party members that constitutes one of the most secretive aspects of China's one-party system.

Four years into President Xi Jinping's sweeping war on corruption, rights campaigners warn that a key aspect is undermining the very rule of law the party says it is trying to strengthen.

The report released Tuesday focuses on the widespread use of "shuanggui" — a system of detention and interrogation of party cadres at off-the-books sites outside of the criminal justice system.

Human Rights Watch said it analyzed 35 detailed cases involving shuanggui reported in the media.