In a sign that the No Dirty Gold campaign is getting more confrontational, it has targeted singer-songwriter Alicia Keys in a letter-writing campaign to persuade her not to appear in ads for the World Gold Council.

The campaign said 2,500 supporters have written to Keys’s publicists and management team. The letters urge Keys “not to associate herself with gold mining that is directly connected to conflict, human rights abuses, and severe environmental problems in Africa and elsewhere.”

The World Gold Council was not available for comment.