BEIJING, Feb. 7 -- Some U.S. officials are "extremely irresponsible" to accuse China over a so-called plan to set up an Air Defense Identification Zone (ADIZ) over the South China Sea, a spokesman said on Friday.

"Some U.S. diplomats have made groundless accusations against China without verifying the claim," Foreign Ministry spokesman Hong Lei told a daily news briefing.

Last week, Japan's daily newspaper Asahi Shimbun reported that China had drafted proposals for an ADIZ over the South China Sea.

Danny Russel, the U.S. assistant secretary of state for East Asian and Pacific affairs, repeated warnings to China not to impose an ADIZ, which would call on planes to report to Beijing, over the South China Sea.

Hong said the allegations are aimed to shift international attention from and cover up the plot to change Japan's pacifist constitution and expand its military power.

China, as a sovereign country, has legitimate rights to adopt all measures, including setting up an ADIZ, to safeguard national security. No one should make irresponsible comments on this, Hong said.

"We hope the U.S. can do more to contribute to the healthy and stable growth of our relationship," Hong said.