Chinese officials have been accused of rushing construction of the world's longest sea bridge to open for the Communist Party's 90th anniversary, with nuts left unfastened, state media said Thursday.

In the haste to finish the bridge before the July 1 celebrations, nuts on guard rails were in place but not fastened on a roughly 15-metre section of the 36.5-kilometre (22.7-mile) Jiaozhou Bay Bridge, the Global Times said.

The lighting system also had not been installed before it opened on June 30 and it would take at least two months to finish all the bridge's features, state-run China Central Television reported earlier this week.

"Time was running out," a construction worker told state television as he tightened nuts on the guard rails.

The Global Times newspaper quoted Han Bin, a bridge expert at Beijing Jiaotong University, saying: "In order to present a gift for July 1, some works were unable to be finished before the bridge rushed to open to traffic."

"If accidents occur and hit the guard rails, problems might rise."

The dates for openings of major infrastructure projects in China often coincide with the anniversary of the ruling Communist Party on July 1 or the October 1 National Day to showcase the government's achievements.

Despite the rush, the chief engineer for the Jiaozhou Bay Bridge insisted the structure was safe and ready for traffic, the official Xinhua news agency said Wednesday.

"The status of secondary features does not affect the main project or the opening of the bridge," Shao Xinpeng was quoted saying, adding the lighting system was only aesthetic.

Internet users were not convinced, accusing engineers and local authorities of putting propaganda ahead of safety as they posted video and photos of the yet to be completed bridge online.

"Infrastructure projects opened earlier than scheduled for window-dressing could lead to chaos and even horrible disasters, which are not rare," one web user said in a post on Weibo, a popular twitter-like microblogging service.