TAIPEI, Oct 6 Reuters Taiwan39;s government has opened an investigation into four companies named in a media report as conducting business with firms linked to U.S.sanctioned Huawei HWT.UL in China, and is considering tighter rules on key technologies.

Taiwan Economy Minister Wang Meihua said the ministry would be looking into whether the firms39; activities in China matched up with their initial investment approval from the island39;s government.

If not, then the highest permitted fine is up to T25 million 775,300, she said.

Wang did not give details on what rules the companies might have broken. She said earlier this week they had been engaged in lowend work like handling waste water.

A Bloomberg news report this week said the firms had been working with Huaweiconnected firms to build infrastructure for chip plants.

The companies Topco Scientific 5434.TW, LK Engineering 6139.TW, United Integrated Services 2404.TW and CicaHuntek Chemical Technology Taiwan 6725.TWO  have all denied any wrongdoing.

Huawei did not immediately respond to a request for comment. China is in the middle of its long National Day holiday.

Wang also said Taiwan39;s government will soon unveil tighter rules on key technologies, taking into account international practice, she added, without giving details.

The Chinese telecommunications giant has, for the last four years, been barred from obtaining components and technology from U.S. firms without approval.

While many Taiwanese tech…