BEIJING - A total of 3.94 million computers in China were infected by viruses in December 2011, a national computer security monitoring center said Tuesday.

The number of infected computers in December dropped by 45.73 percent, or 3.32 million, from November, the National Computer Network Emergency Response Technical Team/Coordination Center of China (CNCERT/CC) said in a report released Tuesday.

Nearly 65 percent of the December cases were traced to the Conficker computer worm, which was first detected in 2008, the center said.

The number of Chinese websites that were falsified in December increased by 12.9 percent month-on-month to 2,016, including 163 government websites, the center said.

The CNCERT/CC is a national organization that provides computer network security services and technological support.