Transparency Solomon Islands is urging the government to investigate claims that mercury is being used at the gold mine on Guadalcanal.
Gold Ridge is operated by a subsidiary of the owner, the Australian company St Barbara Limited, but Transparency's chairperson says there are up to 200 illegal miners working in the pits every day.
Ruth Liloqula, who is also a community relations officer for Gold Ridge, says Transparency understands some of the operators are either using or going to get the local miners to use mercury for extraction.
She says that poses enormous risk to the environment.
"The possibility of what is happening in Ghana where the use of mercury and no attention is paid to environmental damage and river system pollution. So we need the government to follow the law - the law is pretty good. But at the moment we are not following it."
Transparency Solomon Islands' Ruth Liloqula.