The unprecedented concessions come as China pursues record M&As abroad to offset slowing economic growth at home and a weakening currency. They also come as U.S. scrutiny of Chinese-initiated M&A remains high, making its partners uneasy and forcing several deals to be abandoned.

"These are unusual behaviors and just show that the Chinese want to get the deals done," said one Hong Kong-based technology banker, who declined to be identified because the person was not authorized to speak to the media.

The stakes for China are particularly high in the technology sector as Beijing seeks to become a global semiconductor powerhouse, relying mainly on offshore M&As to achieve its goal.

The biggest concerns are about the Committee on Foreign Investment in the United States (CFIUS), an interagency panel that scrutinizes deals for national security concerns. CFIUS, which comprises 16 U.S. government departments or agencies, does not publish its decisions or its reasoning for them.

Reflecting CFIUS worries, China's HNA agreed last month to a hefty $400 million in reverse termination fees for its $6 billion purchase of electronics distributor Ingram Micro (>> Ingram Micro Inc.). This was the first time any material break-up fee was introduced in a U.S. deal covering CFIUS, bankers familiar with the matter said.

The usual break-up fee is about 1-1.5 percent of a deal's value, but HNA agreed to pay 6.6 percent. And China Resources Microelectronics and Hua Capital agreed to pay a total of $200 million in termination fees, or 8 percent of the deal value, to buy Fairchild Semiconductor International (>> Fairchild Semiconductor Intl Inc).

The previous largest CFIUS-related termination fee was $30 million when commodity trader Glencore (>> Glencore PLC) offered $6.2 billion to buy Viterra in 2012.

PULLED DEALS

China's goal to become a global semiconductor powerhouse has meant prized U.S. tech assets are a focus of its overseas deals. The value of China's announced outbound M&A into the United States has already hit a record $23 billion this year, more than double that of the whole of 2015, according to Thomson Reuters data.

But in a sober reminder of the U.S. regulatory hurdles, deals worth $10 billion involving U.S. targets have been pulled just this year alone. That includes China's Unisplendour Corp's (>> Unisplendour Corporation Limited) $3.78 billion investment in U.S. hard-disk maker Western Digital Corp (>> Western Digital Corp).

And, for a third straight year in 2014, China was the country whose planned U.S. acquisitions and investments were the most scrutinized by U.S. regulators for security implications, according to a report by CFIUS.

To mitigate the extra scrutiny, Chinese companies are seeking joint ventures as opposed to an outright purchase, bankers said.

"People are definitely talking about doing more non-control deals," said James Lidbury, a partner with law firm Ropes & Gray.

"A minority stake buy is still doable, but a board seat is problematic. It would also help if you are privately owned, but still there will be a lot of questions from CFIUS in the course of the review," he added.

Yet another way to sidestep the added scrutiny is to aim for mid-sized deals and focus on sectors which are less sensitive, M&A bankers said. The recent $640 million deal by China's Suzhou Dongshan Precision Manufacturing Co (>> SZ Dongshan Precision Manufacturing Co) to buy printed circuit board maker Multi-Fineline Electronix (>> Multi-Fineline Electronix, Inc.) is a case in point, they said.

"You want to avoid the headline grabbing tech deals this year. I would think anything between $1 billion and $3 billion can still be done," said a senior Hong Kong-based M&A banker, who was not authorized to speak to the media.

(Additional reporting by Liana Baker and Greg Roumeliotis in NEW YORK and Miyoung Kim in SINGAPORE; Editing by Muralikumar Anantharaman)

By Denny Thomas