China voiced opposition on Tuesday to Washington's controversial plan to deploy a missile defence system in some East European countries, saying it could shift the strategic balance of power.

The United States wants to locate elements of its planned shield -- including a radar station and interceptor missiles -- in Poland and the Czech Republic.

"The Chinese side has always held that missile defence impacts the strategic balance and stability," Chinese Foreign Ministry spokeswoman Jiang Yu said when asked about the U.S. plan, which has drawn angry warnings from Russia.

"It is not conducive to mutual trust between major powers and also regional security," Jiang told a news conference. "It can also bring new proliferation problems."

The United States says the shield is not a threat to Russia but is designed to protect against possible missile attacks from what it calls "rogue states" such as Iran and North Korea.

But Moscow is convinced otherwise and President Vladimir Putin has vowed to aim missiles once again at Europe if the United States pursues its plan.

China also has worries of its own.

Tokyo and Washington have begun installing a missile shield in and around Japan to ward off potential threats from North Korea.

Beijing is concerned that the United States might use the system to shield Taiwan.

The United States pulled out of the 1972 Anti Ballistic Missile treaty in 2002 so it could begin deploying its missile defence shield.