COSCO executive director Minjie Xu, under investigation for corruption, has resigned all his posts at China's biggest shipping line for "personal reasons", according to the parent company.

Xu is also executive vice president of China Ocean Shipping, vice chairman of China International Marine Containers Group Co and chairman of Cosco Logistics.

Former Cosco chairman Captain Wei Jiafu, who stepped down in July, has also been prevented from leaving China, the Beijing Times reported, citing unidentified company sources. This report has been posted by Xinhua.

The resignation follows Cosco's announcement that Xu was "under investigation by a relevant regulatory body", adding that it "stands firmly behind the party and the country's policy of anti-corruption investigations and [welcomes] public, news media and society at large scrutiny."

The company said it "will assess the impact of the investigation on the group from time to time based upon the development of the investigation," but did not expect a "material adverse effect".

China Cosco Holdings recently expressed confidence that it will achieve its financial goals for 2013, which would help it avoid delisting from the Shanghai Stock Exchange. The company reported losses in 2011 and 2012 because of weakness in shipping markets.

"The anti-graft efforts by the new leadership are unprecedented," said Hu Xingdou, a professor at the School of Humanities and Social Sciences at Beijing Institute of Technology.

"The investigations may help the leadership implement market-oriented reforms at state-owned enterprises that are monopolies at the moment," he told Bloomberg.