Western sanctions against Russia may slow down exploration for oil and gas on both the Norwegian and Russian side of the Arctic Barents Sea, lobby group Norwegian Oil & Gas told Reuters on Wednesday. "We have many members working on both sides of the border, where coordination of fields will be a key topic. Collection of seismic and other joint activities may be affected," said the group's head of legal affairs, Oluf Bjoerndal. The association represents oil firms, including most supermajors, as well as some of the world's biggest oil and gas service firms. "We fear that this could become a problem. There's a worry about that. It may mean that some areas aren't explored well enough, that potential discoveries are delayed," he added.