Two Luxembourg-registered subsidiaries of Malaysia’s national oil company Petronas have been seized on behalf of descendents of the former sultan of Sulu, after a French arbitrator ruled that they were entitled to $14.9 billion relating to an historic land lease agreement in the oil-rich state of Sabah, which today is part of Malaysia.

The move is part of legal efforts launched five years ago by the Sulu heirs to win compensation over land in Sabah they claim their ancestor leased to a British trading company in 1878, before the discovery of vast natural resources in the area.