Southern African leaders declared Tuesday that Zimbabwe's rival parties had agreed to form a unity government, but the opposition said that was not the case. The continuing impasse leaves Zimbabwe embroiled in a prolonged and violent political crisis that has ruined a once-prosperous nation: half the population of the former food exporter faces starvation and a cholera epidemic caused by the collapse of water services has already killed almost 3,000 people. In a communique, nine nations' leaders and Cabinet ministers from four other countries said a Zimbabwean prime minister, the post opposition leader Morgan Tsvangirai is to hold, will be sworn in Feb. 11 after Parliament passes a constitutional amendment creating the post. Ministers would be sworn in Feb. 13, the statement from the regional bloc said.