SHANGHAI, Aug. 24 -- MORE than one million computers were infected by Trojan programs on the Chinese mainland in the first half, 21 times more than last year, a state-level Internet security organization said yesterday.

Some of the programs were written by hackers in other countries and regions, especially Taiwan and the United States, according to the National Computer Network Emergency Resource Technical Team/Coordination Center of China.

Trojan programs are sometimes used to steal personal financial information and can result in substantial monetary losses. They are also used by malicious hackers to delete computer files.

The one-million infections in the first six months compared with 44,717 computers for all of 2006, according to the computer emergency center.

"Hackers used to spread viruses for fun or self-expression, but today they have clear financial targets," said Dai Guangjian, an expert at Kingsoft Corp, a Beijing-based antivirus firm.

Sixty-two percent of the cyber bugs detected in the first half were Trojan programs designed to steal personal information, including passwords for online bank and game accounts, according to Beijing Rising, another anti-virus firm.

Shanghai ranked No. 1 with 17 percent of all computers infected, followed by Beijing's 12 percent and Jiangsu Province's 9 percent, according to the center.

Nearly 78,000 computers were infected by programs spread from overseas Internet addresses. Among them, 42 percent came from Taiwan and 25 percent from the United States, according to the center.

About 8,000 overseas servers were found to control infected corporate machines on the Chinese mainland, the organization said.