China's Ningbo Port Co Ltd will join hands with Denmark's giant port operator A.P. Moller-Maersk to expand the third-biggest port in China with a total investment of 4.29 billion yuan ($673.4 million), the Chinese companies said in filing to the Shanghai Stock Exchange on Friday.

Ningbo Port Group and APM Terminals and A.P. Moller-Maersk will set up a joint venture to invest and operate berths 3, 4 and 5, comprising a one kilometer quay in Ningbo's Meishan Container Terminal, the statement said.

Ningbo Port Co Ltd will invest 1.44 billion yuan into the joint venture, and takes up a 67 percent stake. An affiliate company under Maersk will invest 7.08 billion yuan and takes up a 33 percent stake.

Ningbo is the sixth-largest container port in the world and the third-biggest in China.