Factbox: Google complaints add to list of Sino-U.S. disputes

(Reuters) - Internet giant Google''s January 12 threat to quit China, citing cyber attacks and tightening censorship, could add to strains between Beijing and the United States, already at odds over currency, trade and Taiwan.

With the two giant nations joined at the hip economically, Sino-U.S. tensions are unlikely to escalate into outright confrontation, but could make cooperating on global economic and security issues all the more difficult.

Here are the main sources of tension:

CURRENCY AND DEBT

The United States complains that China keeps its currency artificially undervalued, thus giving its exporters an unfair advantage.

China has unofficially pegged its currency to the dollar since mid-2008, meaning its currency has weakened against other trade partners as the value of the dollar has slid.

Beijing is concerned the value of its dollar holdings could be eroded by massive debt issuances to fund the U.S. stimulus.

China held $798.9 billion in U.S. Treasuries at end-October, displacing Japan in September 2008 as the largest foreign holder.

TRADE AND INVESTMENT

China is requesting the World Trade Organization open a dispute panel over U.S. duties on tires, after the United States for the first time imposed safeguard duties China had agreed to when it joined the WTO.

Other trade disputes center around steel products, poultry, Chinese tariffs on raw materials exports, and quality and safety concerns over Chinese-made food, toys and other goods that Chinese manufacturers view as a type of protectionism.

U.S. firms investing in China complain about intellectual property theft, murky regulations, corruption and unfair advantages enjoyed by domestic rivals.

China complains about investment barriers on the U.S. side, citing resource investments blocked on national security grounds.