U.S. President George Bush has joined calls for Zimbabwe's president, Robert Mugabe, to step down, but the African Union is rejecting tougher action against the long-time leader.

In a statement Tuesday, Mr. Bush said "it is time for Mr. Mugabe to go."  He called on more Africans to demand an end to what he termed Mr. Mugabe's "tyranny."

But a spokesman for AU chairman and Tanzanian President Jakaya Kikwete said today that only dialogue and not military action can resolve Zimbabwe's problems. 

Those problems include a cholera outbreak that has killed nearly 600 people, food shortages, hyperinflation and a stalemate in efforts to form a new government.

Zimbabwe's information minister, Sikhanyiso Ndlovu, Tuesday insisted the cholera situation is under control.  He also dismissed world leaders calling for Mr. Mugabe's resignation, saying he does not want to hear, in his words, "their dirty mouths."

French President Nicolas Sarkozy, European Union foreign policy chief Javier Solana and Kenyan Prime Minister Raila Odinga are among the other leaders that have said Mr. Mugabe should resign.  Mr. Odinga said foreign troops should be sent to take control of Zimbabwe's dire humanitarian situation.

A South African Foreign Ministry official said Tuesday that he cannot see South Africa deploying forces to its neighbor.  The official, Ayanda Mstaluba, said the South African government remains focused on urging Zimbabwe's ruling party and opposition to reach a power-sharing agreement.

Negotiations have dragged on for months following disputed presidential elections earlier this year.  The lack of an agreement has left Zimbabwe without an official government, and worsened the decline of the country's health care system. 

The World Health Organization said today that the number of cholera cases in Zimbabwe stands at nearly 14,000.  It warned that 60,000 people could be infected if the epidemic gets further out of control.

Some information for this report was provided by AFP, AP and Reuters.