The Zimbabwean officers behind the military action in Harare insist they have not stolen power but are merely acting to purge "criminals" from Mugabe's political entourage.

But others, including AU chairman President Alpha Conde of Guinea have warned the operation has all the hallmarks of a coup d'etat, which could see Zimbabwe kicked out of the body.

Chergui said the AU would remain "vigilant" but "for the time being we hope Sadc will succeed in defusing the tensions and promote ... a peaceful solution to what is happening there."

The senior African Union commissioner was speaking after talks in Washington with the State Department on closer cooperation between the African Union and the United States.

His host, US acting assistant secretary for African affairs Don Yamamoto said that on Zimbabwe "we agree totally and completely with our African Union colleagues."

But he also cautioned that whatever government emerges from the crisis must pursue "political, economic, constitutional reform" if it ever hopes to be taken off "numerous sanctions lists."