The United Nations says Zimbabwe's government has canceled a visit by a U.N. torture investigator who was to examine alleged attacks on opposition party members.
The U.N. human rights office says Manfred Nowak was in South Africa on his way to Zimbabwe for a week-long trip that was scheduled to begin Wednesday.
It says the Zimbabwe government canceled the visit at the last minute, citing talks with southern African leaders over the country's fragile power-sharing agreement.
The U.N. has not said whether the visit will be rescheduled.
The opposition Movement for Democratic Change has accused members of unity government partner ZANU-PF of harrassing its supporters through beatings and arbitrary arrests.
On Tuesday, the MDC said unidentified gunmen assaulted and tried to kidnap a security administrator.
The MDC and ZANU-PF have been at nearly constant odds since forming the unity government eight months ago.
On October 16, the MDC announced that it would no longer work with ZANU-PF.
Ministers from the Southern African Development Community's body on politics, defense and security will discuss the stand-off on Thursday in Harare.
Some information for this report was provided by AFP and AP.