Britain called for tough action as well as talk in the face of Zimbabwean President Robert Mugabe's defiance and signs of disunity among his opposition. British Foreign Secretary David Miliband urged South Africa and the rest of the international community on Sunday to "unite behind a tough, strong, clear (UN) Security Council resolution" calling for international sanctions against Mugabe. Miliband spoke to reporters after visiting a downtown Johannesburg church that is a refuge for Zimbabweans fleeing their homeland's political and economic crises. South Africa, though, has said the proposed resolution could undermine President Thabo Mbeki's attempt to mediate between Mugabe and opposition leader Morgan Tsvangirai. The US-drafted resolution backed by Britain would require nations to freeze the financial assets of Mugabe and 11 of his officials, and to restrict their travel to within Zimbabwe.