Two senior managers at the parent company of China Southern Airlines are being investigated over allegations that they used their positions to commit crimes, the carrier said on Tuesday.

Chen Gang was deputy general manager of China Southern Air Holding Co, and Tian Xiaodong was the company's operations director.

Both have been removed from their positions, and the airline - the country's largest by fleet size - said its operations will not be affected.

The announcement comes just over a year after the carrier confirmed that four mid-ranking executives were under police investigation for alleged corruption. The names of the four were not revealed, but a source said Yu Siyou, deputy director of the marketing management committee, was among them.

Chen was director of the same committee, which supervises sales as well as marketing, before being promoted.

China Southern Airlines suffered a 1.01 billion yuan ($170 million) net loss in the first half of the year, compared with a 302 million yuan profit in the same period in 2013.

It was the worst financial performance by any of the main domestic carriers, though the company's financial performance is believed to be improving because of the recent fall in the price of fuel.

The campaign by the Central Commission for Discipline Inspection began in May 2013, and the efforts to fight corruption and other misconduct in State-owned enterprises intensified this year.