HONG KONG (Reuters) - Chinese tech giants Alibaba Group Holdings BABA.N and Tencent Holdings 0700.HK will be among new investors pouring a total of around $10 billion into mobile carrier China Unicom, sources said, part of efforts by Beijing to rejuvenate state behemoths with private cash.

FILE PHOTO: Two men chat beside a logo of Alibaba (China) Technology Co. Ltd at its headquarters on the outskirts of Hangzhou, Zhejiang province May 17, 2010. REUTERS/Steven Shi/File Photo

Four sources with knowledge of the matter told Reuters that Alibaba and Tencent would invest in the Shanghai-listed unit of the telecoms group - China United Network Communications Ltd 600050.SS - as part of the capital-raising effort.

One of the sources said Alibaba and Tencent would lead the group of investors, while Baidu BIDU.O, the third of China's constellation of tech giants, has pulled out. The source did not comment on the reason for that decision.

China Unicom, formally known as China United Network Communications Group Co Ltd, plans to raise around 70 billion yuan ($10.25 billion) through the Shanghai unit, the sources said. That would mark the largest capital raising in Asia since the initial public offering of insurer AIA Group 1299.HK in 2010, according to Thomson Reuters data.

About 50 billion yuan would be raised through new share issues, while China’s second-largest telecom carrier would also sell part of its stake in the Shanghai-listed unit, two of the sources said. The sources could not be identified as the negotiations are not public.

Other potential investors approached by China Unicom, named last year as part of a pilot mixed-ownership reform scheme, include the country’s other major internet firms and some state-backed institutions, such as China Life Investment Holding Co Ltd, one of the sources said.

Alibaba, Tencent and other potential investors have yet to finalize the terms of any purchase, the sources said, though the deal is likely to be finalised by this summer.

China United Network did not respond to requests for comment. China Unicom Group and China Life Investment Holdings could not immediately be reached. Alibaba, Baidu and Tencent declined to comment.

The State-owned Assets Supervision and Administration Commission (SASAC), which oversees state-owned enterprises (SOEs), also did not respond to a request for comment.

IN THE RED

China Unicom is one of China's three major state-owned telecom firms, along with China Mobile 0941.HK and China Telecom 0728.HK, but also the weakest.

It is one of the world’s largest mobile carriers by subscribers, but competition in China is cut-throat and its earnings have struggled in recent quarters. Private firms have shot ahead in developing cloud and big data services as well as mobile software.

China Unicom is widely seen as over-staffed, inefficient and slow to develop key technologies - prompting Beijing to add it last year to the first batch of SOEs who would see mixed-ownership reform.

In March, its Hong-Kong listed arm, China Unicom Hong Kong Ltd 0762.HK, reported a 94 percent drop in profit for 2016.

China has thousands of state-owned enterprises, many of them bloated and debt-ridden, and its mixed-ownership reforms are aimed at reviving the sector with private capital, creating stronger conglomerates capable of competing on the global stage.

The central government issued guidelines in 2015 aimed at overhauling its SOEs, saying it would close down the most uncompetitive firms and modernize the ownership structure of those that remained.

Earlier this week, the official China Securities Journal said China had completed 48 deals by June 20 to allow private capital to invest in government-run enterprises - up ninefold compared with the same period last year. And that would accelerate, it said.

Other SOEs selected to carry out Beijing’s pilot mixed-ownership reform scheme include China Eastern Air Holding [SASAHW.UL], China Southern Power Grid [CNPOW.UL] and China State Shipbuilding Corp [SASACN.UL].

China Eastern Air earlier this week sold almost half of its freight unit to four firms, including Legend Holdings 3396.HK and Global Logistic Properties GLPL.SI, in the Chinese aviation sector's first mixed-ownership reform deal.

China Unicom’s Shanghai-listed unit said in early April it would be part of the mixed-ownership pilot, but gave no details. The stock, whose market value exceeded $23 billion as of late March, has been halted from trading since then.

Mixed-ownership may not be welcomed by listed companies, pushed to invest in state firms, but the need for government support is great even for China’s largest private conglomerates, analysts said.

For China Unicom, analysts said mixed-ownership reform could be a game-changer - even if substantial restructuring will be difficult, with or without private investors.