HONG KONG (Reuters) - A unit of China's Fosun Group and Shanghai Pharmaceuticals Holding Co 601607.SS are among bidders for a stake in U.S. speciality drugmaker Arbor Pharmaceuticals LLC, the companies said on Monday.

Signs are seen on the headquarters of Shanghai Fosun Pharmaceutical Group in Shanghai, China, March 29, 2016. REUTERS/Aly Song/File Photo

The bids come as Chinese companies face tightening scrutiny on their overseas investments. Chinese regulators are reviewing deal agreements in minute details, and have cracked down on some large domestic conglomerates, including Fosun, for their debt-fuelled acquisitions abroad.

Shanghai Fosun Pharmaceutical Group Co Ltd 600196.SS said in a stock exchange filing its Hong Kong unit submitted on July 19 a non-binding bid for a stake in Arbor, which is backed by private equity firm KKR & Co LP KKR.N.

In a separate filing, Shanghai Pharma also said it had submitted a non-binding bid for a stake in Arbor on the same day.

Both companies did not disclose the quantum of stakes they had bid for nor the financial terms but said they have not entered exclusive talks with the seller.

Fosun Pharma said its Hong Kong unit will begin conducting due diligence to determine further steps.

Arbor has appointed Bank of America Merrill Lynch to run the sale process, which has attracted around half a dozen preliminary bids, mostly from Chinese companies and private equity firms, according to people familiar with matter. The bank did not immediately respond to a Reuters request for comment.

Some of the bidders may seek to acquire control of the company, said two of the people, adding that discussions are at an early stage still.

A potential deal could value Arbor at around $3 billion, two of the people said.

Bloomberg, which first reported on the sale process, said the bidders were seeking to buy 20 percent to 30 percent of Arbor.

Arbor did not immediately respond to a Reuters query for comment. The sources could not be named as the discussions are confidential.

Atlanta-based Arbor produces mainly branded prescription drugs for the paediatric, hospital and cardiovascular markets.

New York-based KKR agreed to buy more than a quarter of shares in the company in December 2014, in a deal that valued privately held Arbor at over $1 billion, Reuters reported at the time.