The Ministry of Finance website was accessible only intermittently for most of Wednesday, amid speculation that stock investors had hacked the site because of the ministry's previous denial of a move to raise the stamp fee on securities trading.

"We are not sure of the reason for the site's failure, although we can log on to it through our Intranet," an employee of the website department, who did not want to be named, said at 7 pm yesterday. The site was accessible by 11 pm.

The ministry's spokesperson was not available for comment.

A network security expert from Beijing-based Rising Anti-Virus Software company said it's difficult to pinpoint the reason for the site's failure, although hacking is one possible explanation.

There were reports that the attack was launched by frustrated stock investors who were angry at the ministry's denial of a rise in the tax on May 22.

A ministry spokesperson said in a May 22 interview that he had not heard of any plan to raise the stamp tax, according to China Security News.

The tax on securities trading was tripled from 0.1 percent to 0.3 percent from yesterday after an announcement late on Tuesday night, triggering a 6.5-percent slump on the Shanghai stock exchange.

"The sudden hike, coming after the denial, could have upset investors," said Ding Shengyuan, deputy research director of China Galaxy Securities.