Zimbabwe's president signs into law a new constitution and vows to hold peaceful and clean elections later this year.

President Robert Mugabe said Wednesday the new constitution, unanimously accepted in a March referendum, has shown that Zimbabweans are united, regardless of political affiliation and without outside interference.

The constitution stipulates new voting procedures and reforms to be implemented from the signing date so that the earliest new elections can be held is Aug. 14.

Zimbabwe is hosting a worldwide United Nations tourism summit in mid-August, suggesting that nationwide polls would take place in September after what is expected to be the world's largest tourism exposition.

Several parts of the new constitution are effective immediately with others set to come into force after the swearing in of the next elected administration.