Work on a Chinese skyscraper aiming to be the world's tallest building has been ordered to stop just days after breaking ground, local media reported Thursday.
"Relevant authorities" had ordered a halt to work on the Sky City tower in Changsha, in the central province of Hunan, "because it did not complete the required procedures for seeking approval to start construction", the Xiaoxiang Morning Post newspaper said.
At 838 metres (2,749 feet), the tower would surpass the world's current tallest skyscraper, the Burj Khalifa in Dubai, by 10 metres.
Ground was broken on the project at the weekend, the company behind it, Broad Group, said earlier this week, adding that construction would take just four months once the foundations were laid.
The construction schedule has added to concerns over safety, with worries over whether the land surrounding the site could support the structure's tremendous weight.
Certain approvals were needed to assess the project's safety and environmental impact, the Xiaoxiang Morning Post said, citing unnamed authorities.
But a Broad Group spokeswoman told AFP it had all the required permits.
The company -- whose founder Zhang Yue made a fortune from air conditioners -- attracted global attention last year for building a 30-storey tower in just 15 days, using prefabricated units stacked on top of one another.
It had planned to use the same technique to assemble Sky City by the end of last year, but construction work was delayed multiple times amid concerns that the plans were overambitious.
The People's Daily, the official paper of China's ruling Communist Party, has criticised the project, calling it "blind worship for ultrahigh skyscrapers" on Sina Weibo, a Chinese Twitter-like service.
China is home to three of the world's 10 tallest buildings, said the research group Emporis.
A 2011 report said China could boast four times as many skyscrapers as the United States has within five years.