The controversial 55-kilometre Hong Kong–Zhuhai–Macau Bridge opened Tuesday with an official ceremony attended by Chinese President Xi Jinping. 

Fireworks played on a screen behind him at the ceremony, which was also attended by Hong Kong Chief Executive Carrie Lam and Chinese Vice Premier Han Zheng, according to the South China Morning Post.

The mega bridge will help further integrate Macau and Hong Kong, two former European colonies that were returned to Chinese rule in the late 1990s, with mainland China, Han said in a speech. 

"It facilitates the people of all three places for greater exchange in economics and trade," the SCMP quoted Han as saying. "It also enhances the competitiveness of the Pearl River Delta."

Beijing also hopes it will help develop the western Pearl River Delta by reducing travel times from Zhuhai to the port of Hong Kong from 3.5 hours to 75 minutes. Travel times to Hong Kong’s airport will also be cut from four hours to 45 minutes, according to the bridge authority. 

With its opening, the project has become the world’s longest sea bridge, which has taken nearly 10 years to complete. It will open to the public on Wednesday.

The bridge’s main access road to Hong Kong’s port, however, will not be completed until next year, according to the SCMP, in one of a number of scandals that have tarnished the project’s image in the autonomous Chinese city. 

Other incidents have included a two-year delay in opening, massive budget overruns, faked testing of construction materials, and the death of 10 workers on the Hong Kong side of the project. 

Critics say the project is largely unnecessary as Hong Kong and Macau are already connected to mainland China by train, ferry, and air transit in addition to existing road links. 

The bridge can also not be directly accessed by the public but requires applying for separate driving permits depending on the direction of traffic. The public, however, can take a bus, shuttle or hire a designated private car to travel across the bridge. 

On Tuesday, the Dolphin Conservation Society told broadcaster RTHK that construction of the bridge has led to a more than a 40 per cent decline in local populations of the critically endangered Chinese white dolphin, which is also a symbol of Hong Kong.