The Hong Kong-Zhuhai-Macao Bridge moved a step closer to completion on Wednesday morning as two main bridge structures were connected.

Lawmaker Lo Wai-kwok, who represents the engineering sector in the city's legislature, described the connection as "a milestone for the world-class project" but said there will still be many challenges before the project is finished.

The Hong Kong-Zhuhai-Macao Bridge Authority said 80 percent of a 6.7-km tunnel has been completed.