In May Hong Kong’s Constitutional and Mainland Affairs Bureau proposed amendments to city’s data-protection laws to combat a practice known as doxing.

Doxing refers to the practice of putting people’ personal information online so they can be harassed by others. The proposals call for punishments of up to 1 million Hong Kong dollars, the equivalent of about $128,800, and up to five years imprisonment.

Facebook, Twitter and Google have privately warned the Hong Kong government that they could stop offering their services in the city if authorities proceed with the planned changes to their data protection laws. The changes could make the companies liable for the malicious sharing of individuals’ information online.

A letter sent by an industry group that includes the internet firms said companies are concerned that the planned rules could put their staff at risk of criminal investigations or prosecutions related to what the firms’ users post online.

The internet giants pointed out that the only way to avoid these sanctions would be to refrain from investing and offering the services in Hong Kong and to stop investing in the country.