Zimbabwean president Robert Mugabe has pledged to crack down on corruption in the ruling party. Speaking at his party's annual congress, Mugabe admitted that some of his ministers had been soliciting bribes from would-be investors following the passing of a law requiring foreign investors to sell a majority of shares to local businesses. The 88-year-old president also warned he would call elections sooner rather than later if the opposition Movement for Democratic Change failed to come up with a new constitution. Al Jazeera's Haru Mutasa reports from the town of Gweru, where Mugabe was speaking.