BEIJING - A new report has shown booming numbers of attacks on Chinese websites, highlighting severe challenges for the country to address in ensuring Internet security.

Chinese authorities found 36,969 websites had been tampered with in 2014, and backdoors implanted in 40,186 webpages, according to a report released by Internet Society of China and the National Computer Network Emergency Response Technical Team/Coordination Center of China on Friday.

Last year, 4,761 IP addresses in the United States controlled 5,580 Chinese websites through backdoor programs, which can allow them to bypass normal authentication to secure illegal remote access to a computer.

In addition, Chinese authorities detected 93,136 phishing websites in 2014, 2.1 times more than the number reported in 2013.

Phishing attacks are generally accomplished through fraudulent websites that appear legitimate by using addresses or login pages that mimic those of authentic sites.

China's netizen population, the world's largest, had reached 649 million by the end of 2014.