Zimbabwean opposition politician Tendai Biti says "we will continue to fight for truth and justice" after the Constitutional Court threw out a bid by his MDC Alliance to annul the presidential results.

"Legitimacy comes from the people and the people alone," he said in a tweet.

Mr Biti was released on bail earlier in August after appearing in court on charges of inciting violence after he was deported from Zambia.

At least six people were killed two days after the vote in clashes between security forces and MDC Alliance supporters who alleged that their leader, Nelson Chamisa, had been robbed of victory.