Southern African leaders will begin an emergency summit in Johannesburg on Friday to discuss the deadlock in talks to end the political crisis in Madagascar.

The summit follows the decision this week by mediators from the international community, including the African Union (AU), to suspend discussions with rival parties in Madagascar.

The South African government announced Thursday that President Jacob Zuma would host an extraordinary summit of heads of state and government on Friday and Saturday in his capacity as chairman of the Southern African Development Community (SADC).

SADC, the African Union and the United Nations have been trying to broker an end to the stand-off which began when  opposition leader Andry Rajoelina seized power from President Marc Ravalomanana in March. Both SADC and the AU have condemned Rajoelina's takeover and called for the country to return to constitutional rule.

Mediators announced last month  that Malagasy parties had agreed to hold elections within 14 months, but talks since then have stalled.

Ravalomanana said in a statement issued Thursday in South Africa - where he is now living - that he intended joining "this  critically important summit."

In Washington, DC, a spokesman for the United States government issued a sharp condemnation of "the unconstitutional actions that led to the current situation" and urged political parties to return to talks.

"We continue to believe that the only way to resolve this crisis is through a consensual political process leading to elections at the earliest possible date," said Ian Kelly, a spokesman for the U.S. State Department.

"We... categorically reject the use of force as a means to resolve this crisis. We remain impartial and will not support unilateral solutions by particular political factions, as such moves would not produce a lasting solution based on credible, unbiased elections," Kelly said.