BEIJING (REUTERS) - China's ruling Communist Party announced a corruption investigation into a one-time senior aide to former president Hu Jintao on Monday, as President Xi Jinping opens another front in his sweeping battle against deep-rooted graft.

In a terse and brief statement on its website, the party's anti-corruption watchdog said that Ling Jihua was being investigated for "suspected serious discipline violations", the usual euphemism for graft. It gave no other details.

Ling was demoted in September 2012 after sources said his son was involved in a deadly crash involving a luxury sports car. The car - a Ferrari according to some of the sources - crashed in Beijing in March 2012 in an embarrassment for the ruling Communist Party, which is sensitive to perceptions that children of top party officials live rich, privileged lifestyles completely out of touch with the masses, the sources said.

Ling was dropped from his post as head of the party's General Office of the Central Committee, a powerful post similar to cabinet secretary in Westminster-style governments. He was then appointed as minister for the less influential United Front Work Department, which is in charge of co-opting non-Communists, religious groups and ethnic minorities.

A probe into his older brother, Ling Zhengce, was announced in June, for suspected "serious discipline and law violations".

China's campaign against official corruption has intensified since Mr Xi took over as President, with several senior government figures and state company executives in detention.