Reports suggest diplomatic efforts between Egypt and Hamas in Cairo are progressing.
After meeting Egyptian President Hosni Mubarak, Middle East Quartet envoy Tony Blair said elements were in place for a ceasefire agreement and were being worked on "very hard", AP news agency reported.
The cholera outbreak in Zimbabwe is "the greatest threat ever to face" the country, opposition leader Morgan Tsvangirai has said.
His warning came after health officials said the outbreak, which according to the UN has killed 360 people since August, was under control.
South Africa says it will not stop ill Zimbabweans crossing its borders.
Mr Tsvangirai added that talks on a power-sharing deal with President Robert Mugabe's party had stalled.
"The humanitarian crisis that is now engulfing all Zimbabweans represents the greatest threat ever to face our country," Mr Tsvangirai said in a statement reported by AFP.
