NANJING, May 17 (Xinhua) -- Japanese dairy firm Yakult has signed a deal to expand its factory in the east China city of Wuxi to become the company's largest plant in China, the local government said Thursday.

The move comes as the company is enjoying fast growth in the Chinese market thanks to the popularity of its probiotic dairy products among Chinese consumers.

Yakult will invest 100 million U.S. dollars to expand the plant it built in Wuxi in Jiangsu Province in 2015, adding 15,000 square meters of floor space and six production lines, according to the deal.

The project, expected to be completed in June 2019, will make the Wuxi factory Yakult's largest plant in China with an area of 31,900 square meters and production capacity of an estimated four million units per day.

"Yakult's sales revenue in the Chinese market has continued double digit growth in recent years," said Susumu Hirano, general manager of Yakult (China) Investment Co. Ltd., "The new plant is expected to lay a good foundation for expanding production capacity in China."

"We are happy to see Yakult's fast development in Wuxi in recent years," said Huang Qin, acting mayor of Wuxi, "In the future, we hope Yakult can further expand its operations in the city."

Huang said the city government would provide quality service for the new plant in the future, and expressed hope to deepen cooperation with Yakult.

Yakult, one of the largest probiotic dairy product makers in the world, has four production bases and 42 subsidiaries in China. The Chinese market accounts for more than 10 percent of its global production.