ZHUHAI, China (AP) — China has opened the world's longest sea-crossing bridge linking Hong Kong to the mainland in a feat of engineering that carries major economic and political significance.

Chinese President Xi Jinping attended the ceremony in the city of Zhuhai to cut the ribbon on the 55-kilometer (34-mile)-long bridge linking it to the semi-autonomous regions of Hong Kong and Macau.

The $20 billion bridge took almost a decade to build. It includes an undersea tunnel allowing ships to pass through the Pearl River delta, the heart of China's crucial manufacturing sector.

It's opening will cut travel time across the delta from several hours to just 30 minutes. It also forms a physical link between the mainland and the Asian financial hub, which was handed over from British to Chinese control in 1997.