China--including Hong Kong and Macau--alone saw an average of 2,886 bots per day during 2009. In the same period, there were 722,966 distinct bot-infected computers observed in the country, according to Symantec. Hong Kong, placed third among Chinese cities behind Guangzhou and Shenzhen, accounted for six per cent of China's bot infected computers during the year, the vendor noted.

Accounted for 3 percent of global spam in 2009, China sent 15 percent of the spam emails in Asia Pacific in 2009, compared to 22 percent in 2008.

"In 2009, attackers continued to find sophisticated methods by which to target enterprises and individual users and the greater China region was no exception," said Michael Chue, managing director, Hong Kong & Greater China regional global business. "Driven by increased access to underground tool kits as well as the continued expansion of broadband availability in developing countries, the scale of these attacks reached record levels last year."