A new railway line being built for the August Beijing Olympic Games was a factor in a train crash that left 71 people dead in east China, officials and state press said on Wednesday.
The pre-dawn Monday crash near Zibo city was the most severe in China in over 10 years, also leaving over 400 people injured.
Authorities blamed the accident in Shandong province on the excessive speed of a train from Beijing to Qingdao city -- site of the Olympic sailing competition -- which derailed and slammed into an oncoming train.
According to Zhang Mingqi, vice-head of a cabinet-level investigative team into the accident, orders had gone out to drivers to reduce speed on the section of the track where the accident occurred because of construction on the line.
At the site of the crash workers had dug a more than 20-metre (66-foot) -deep hole that is to serve as the foundations as they link up another railway line from the Shandong capital of Jinan, local officials said.
"This is part of the Jinan-Qingdao line which is being built for the Olympic Games," Zibo city spokesman Li Chenggang told AFP as he pointed out the construction project at the site of the crash.
"The line is expected to be completed before the Olympic Games and will make travel between Jinan and Qingdao much faster."
On April 23, the Jinan Railway Bureau in Shandong printed an order to reduce train speeds on the section of the line under construction to 80 kilometres (48 miles) an hour, Zhang said.
The train was travelling 131 kilometres an hour when it derailed as it rounded a curve near the construction site.
Orders to reduce speed were not properly transmitted to train drivers, the Beijing News said.
But "after this order was issued, no one confirmed that it had been received by the concerned work units (drivers)," the paper said.
Workers on the project, many of whom had assisted in pulling out injured and dead passengers from the Monday wreck, refused to comment on whether their construction work contributed to the wreck.
But Wang Jun, head of the State Administration of Work Safety, said that authorities were also investigating whether the construction work had destabilised the existing track.
"In this investigation we need to clearly grasp factors in several areas, the first is the foundation of the track, whether or not it is stable," Xinhua news agency quoted Wang as saying.
Three top officials of the Jinan Railway Bureau have already been sacked in the aftermath of the accident.
Chinese authorities have scrambled to deal with the fall-out from the wreck, with 19 hospitals in Zibo working overtime to deal with the injured.
"Since the accident yesterday, the work carried out by Zibo city has gone smoothly," Liu Xinsheng, vice-secretary of the Communist Party in Zibo, told reporters Tuesday.
"Now we face the very hard and difficult task of taking care of all those who have been injured."
Train traffic on the line was resumed on Tuesday.
The accident was the second rail tragedy in Shandong this year. In January, a high-speed train ploughed into a group of railway workers in the province, killing 18 people.
However China's railways are generally regarded as relatively safe, if not always comfortable, and they are a primary source of travel for the nation's 1.3 billion people.
Travelling by train is seen as much safer than by road, with 81,000 people losing their lives in traffic accidents last year, an average of around 223 a day, according to China's state-run press.