National Party Leader John Key is expressing deep concern over the developments in Zimbabwe, and is calling for southern African leaders to intensify their efforts to resolve the situation.

"The decision of MDC Leader Morgan Tsvangirai to withdraw from Friday's presidential ballot was probably the only course open to him in the face of mounting atrocities and the clear indication that Robert Mugabe has no intention of respecting the will of the public."

Mr Key said the situation in Zimbabwe was now "desperately serious." 

He called on southern African leaders to now engage in seeking a solution.

"It is pleasing to see that southern African leaders have, in recent days, moved to distance themselves from the tactics of the Mugabe regime.

"That does not change the fact that too many of them have provided cover for Mugabe for too long.

"We now look to the South African Development Community and the African leadership generally to intensify their efforts to find a resolution to the impasse that now exists in Zimbabwe."