(Yicai Global) Jan. 15 -- China's state railway operator in the capital Beijing and surrounding provinces has refuted claims that its newest train carriages feature excessive levels of formaldehyde.

China Railway Beijing Group has denied that carriages on its newest Fuxing high-speed train model contain elevated levels of the carcinogen in a post on Weibo. The rail operator received one carriage from CRRC with excessive levels of formaldehyde and sent it back adding that the state rolling stock maker's Tangshan unit is now addressing the issue.

Excessive levels of the chemical have never been found on trains in services, the operator said, adding that the newest train model is taking longer to enter operation due to longer commissioning processes compared with older trains.

The operator also attributed the prolonged commissioning process to the installation of comprehensive ventilation systems to remove unpleasant odors as part of efforts to make passenger experiences more comfortable.