BEIJING (Reuters) - China's commerce ministry will launch an anti-monopoly probe into Comcast Corp's <CMCSA.O> planned purchase of DreamWorks Animation after receiving unspecified complaints that the U.S. media deal could hurt competition in the Chinese market.

The investigation comes as China's anti-trust watchdog has hardened its stance on companies striking deals without seeking its clearance, with the body naming, shaming and fining almost a dozen firms over the past year for "gun-jumping".

Comcast, owner of NBCUniversal, said in April it would pay $3.8 billion to buy DreamWorks, the producer of the "Kung Fu Panda" and "Shrek" franchises, which was also one of the first Hollywood names to open a production studio in China.

"Recently MOFCOM received complaints regarding Comcast's decision to buy out DreamWorks, claiming that the deal would hurt competition in the Chinese market," Shen Danyang, spokesman for the Ministry of Commerce (MOFCOM) said on Friday. Shen didn't say exactly what the complaints were, nor who made them.

China's film market, the world's second largest, is a magnet for film producers looking to tap the country's 1.4 billion people, even though there are signs that stellar box office growth may be starting to slow.

Reuters was unable to reach Comcast or DreamWorks for immediate comment out of regular U.S. business hours.

Separately, China's commerce ministry said on Friday it would investigate the planned merger of ride-hailing firm Didi Chuxing and the Chinese unit of U.S. rival Uber over anti-monopoly concerns.

(Reporting by Yawen Chen; Writing by Brenda Goh and Adam Jourdan; Editing by Kenneth Maxwell)