The Globe and Mail reports in its Wednesday edition that a potential $4-billion (U.S.) merger between a Barrick Gold subsidiary and Endeavour Mining has been called off following Tanzania's unexpected move to freeze the export of gold and copper ore. The unbylined item quotes Endeavour as saying Tuesday that it had ended discussions with London-based Acacia Mining PLC. Acacia, majority owned by Barrick, also said it had decided not to progress toward a combination. The companies had confirmed "preliminary discussions" in January of a merger that would have created an African mining giant, with mines in five African countries. On March 3, however, the Tanzanian government announced its export ban. "It is expected that all the companies and individuals who were exporting concentrates and mineral ores to foreign countries for beneficiation (processing, smelting or refining) will immediately stop and start doing such activities within the country," the announcement said at the time. Following the ban, Acacia's shares plunged by about 18 per cent on the London Stock Exchange, although they recovered somewhat later. Acacia responded to the ban by halting its gold and copper exports from Tanzania.