(Reuters) -Private equity firm Boyu Capital has emerged as the frontrunner to buy a controlling stake in Starbucks' ( SBUX ) China business in a deal that could value the unit at more than $4 billion, Bloomberg News reported on Tuesday.

Boyu is most likely to clinch the deal after outbidding other private equity firms including Carlyle and EQT, the report said, citing people familiar with the matter.  

Starbucks ( SBUX ) and Boyu did not immediately respond to Reuters requests for comment. 

Reuters reported last month that Starbucks ( SBUX ) had invited about 10 potential buyers to submit their non-binding bids by early September, as the company faces declining market share in key market China due to intensifying competition from local rivals.

The Bloomberg report said other parties, including internet companies, could join the talks as limited partners to help co-finance a deal.

(Reporting by Prerna Bedi in Bengaluru; Editing by Devika Syamnath)