Greenpeace said it was calling on LEGO to review its relationship with Royal Dutch Shell because of the oil company's environmental legacy.
"We're asking LEGO to square the circle between its values and the companies it chooses to endorse," James Turner, a spokesman for Greenpeace International's Arctic campaign, said in a statement.
Greenpeace last week published a 15-page pamphlet expressing concern over a decision by LEGO to put Shell images on toys available at service stations operated by the energy company.
The advocacy group said Shell is building brand loyalty with the next generation of consumers, business leaders and politicians.
In a July 1 response, LEGO said it was being used as a scapegoat for Shell's operations in the arctic.
"We firmly believe that this matter must be handled between Shell and Greenpeace," the company said. "We are saddened when the LEGO brand is used as a tool in any dispute between organizations."