* BAIC now biggest Daimler shareholder

* BAIC disclosed stake because of Daimler Truck listing

* Daimler says underlines successful partnership

BERLIN, Dec 13 (Reuters) - Daimler on Monday said its Chinese shareholder Beijing Automotive Group Co Ltd (BAIC) does not plan to increase its stake in the German luxury carmaker beyond the 9.98% stake it has held since 2019.

The German carmaker said BAIC told Daimler after the Daimler Truck spinoff on Friday that it has held a 9.98% stake since 2019, and does not plan to increase it further.

The statement was the first public confirmation that BAIC's stake has risen from a previously disclosed 5%.

State-owned BAIC has been Daimler's main partner in China for years and operates Mercedes-Benz factories in Beijing through Beijing Benz Automotive.

The two companies have collaborated in areas such as production, research and development and sales since 2003.

BAIC's increased stake means two Chinese companies hold nearly 20% of Daimler, with Zhejiang Geely Holding, owning 9.69% of the German automaker.

Under German financial regulation, BAIC only has to disclose an increase in a shareholding if it were to rise beyond a 10% threshold.

After Daimler's truck division was spun off on Friday, BAIC's stake in Daimler Truck became public information, which also revealed the size of its Daimler stake.

In the Daimler Truck spin off, Daimler shareholders received one Daimler Truck share for every two Daimler shares.

"BAIC received shares in Daimler Truck Holding AG, in relation to their stake in Daimler AG as of Friday. BAIC informed us about the size of their current Daimler stake," a Daimler spokesperson said. "BAIC has not been obliged to disclose the full extent of their holding before today."

Daimler CEO Ola Kaellenius welcomed the information on the size of BAIC's stake, saying in a statement: "We are happy about the engagement of all long-term oriented shareholders, who support our strategy."

Daimler said it holds a 9.55% stake in BAIC Motor and a 2.46% stake in BAIC BluePark.

"The partnership between BAIC Group and Daimler Group has always been a model of Sino-German cooperation," BAIC said in a statement on Monday, confirming the stake figure.

It said it was confident in Mercedes-Benz's potential in the future transformation to electro-mobility.

(Reporting by Riham Alkousaa, Ilona Wissenbach, Brenda Goh, and Victoria Waldersee Editing by Paul Carrel and Jane Merriman)