BEIJING, March 28 -- Cyber attacks from overseas on China's Internet are on the rise, according to a report released on Friday by the country's Internet security watchdog.

Backdoor threats, phishing and trojans or botnets constitute three main forms of attacks, said the National Computer Network Emergency Response Technical Team Coordination Center of China in a report covering 2013.

Last year, 31,000 overseas mainframes controlled 61,000 websites on the Chinese mainland through backdoor programs. Despite an annual decrease of 4.3 percent in the number of mainframes involved, the number of affected websites was up 62.1 percent compared to the previous year.

Some 15,349 websites, about a quarter of the total, were attacked by 6,215 mainframes located in the United States.

Moreover, 90.2 percent of phishing websites targeting Chinese users were running on foreign servers.

A total of 3,823 overseas IPs lured Chinese users to 29,966 fake websites to obtain password and other personal information, up 54.3 percent and 27.8 percent year on year respectively. U.S.-based servers hosted 12,573 fake phishing websites.

In addition, 29,000 overseas servers controlled 10.9 million mainframes on the Chinese mainland via trojans or botnet. Servers originating from the United States hijacked 41.1 percent of all the mainframes, followed by those from Portugal and the Republic of Korea.

The report suggested China maps out a state-level strategy and devise more regulations to enhance cyber security.