A Shanghai Internet company is trying to test the security of its website by offering computer hackers 5,000 yuan ($600) if they can break in, the official Xinmin Evening News said on Monday.

In an unusual one-week trial, the Shanghai Waigaoqiao Free Trade Zone Network Development Co was making the offer for those who could get into its website www.netway.net.cn and obtain documents under the secu.txt section, the newspaper said.

The competition had been approved by local public security authorities, the newspaper said without giving further details.

China has seen a surge in Internet surfers in the past few years with the number of users now estimated at four million. The number of cases of hackers trying to get hold of secure information has also risen sharply, local media have reported.

The website has the following cautionary note, however: "Attempts to break into this site are legal this week only."