(Adds companies saying one of the officials has resigned)
HONG KONG/BEIJING Dec 17 (Reuters) - The Chinese government has questioned two more executives from China National Petroleum Company (CNPC) as part of a wider graft investigation into the state energy giant, two people with direct knowledge of the matter told Reuters.
CNPC and its listed unit PetroChina are at the centre of one of the biggest corruption investigations into the Chinese state sector in years.
Wen Qingshan, CNPC's chief accountant, and Wang Lihua, head of PetroChina's oil trading vehicle Chinaoil, were "taken away" by authorities last week, said the people, who declined to be identified because they were not authorised to talk to the media. Wang is also CNPC's deputy chief economist.
It was not immediately clear whether the two officials were the target of the investigation or were assisting in the broader probe.
Two officials at Chinaoil - Zheng Jun, head of crude oil trading, and a company lawyer who only gave his surname as Chen - said by telephone that the Reuters report on Wang was "totally incorrect".
"Such a thing that you reported has never happened to president Wang," said Zheng. "She is still handling daily management work."
Zheng declined to put Reuters in touch with Wang. Other attempts to reach her were unsuccessful, as were efforts to contact Wen.
One of the two sources told Reuters: "Several officials were taken away by the authorities. One is quite senior. He is CNPC's chief accountant Wen Qingshan. The other officials included ... Wang Lihua."
Calls to CNPC media officials were not answered. PetroChina spokesman Mao Zefeng declined to comment, although PetroChina later issued a statement to the Hong Kong Stock Exchange saying Wen had resigned as a supervisor of the oil and gas producer due to personal reasons.
In a separate statement to the exchange, Kunlun Energy , PetroChina's natural gas distribution arm, said Wen had resigned as chairman for personal reasons.
Wen was appointed chairman in August, replacing Li Hualin, who the company had said was being investigated by authorities.
Zhang Bowen, currently an executive director, would act as Kunlun Energy chairman, the statement said, adding the company had applied to the exchange for its shares to resume trading on Wednesday after they were suspended early on Tuesday.
Beijing stunned the Chinese energy industry in August and September with announcements that five former top executives at PetroChina and CNPC were being investigated for "serious discipline violations" - shorthand generally used to describe graft.
They included Jiang Jiemin, former chairman of both entities.
Authorities have given no further details on what these officials may have done wrong, but the investigations suggest President Xi Jinping wants to tackle graft in an industry that ranks as one of the most powerful corners of the state-owned corporate sector.
Wang has been chief of Chinaoil since 1998. The company has expanded rapidly over the years to become an influential global player in oil markets. (Reporting by Chen Aizhu and Charlie Zhu; Editing by Jason Subler and Dean Yates)