Zimbabwe's rival political parties have agreed on a final draft of a constitution that will be put to a referendum ahead of crucial elections expected this year, President Robert Mugabe said Thursday.

"We are glad to say that we have come to the conclusion of the exercise and all parties are agreed," Mugabe told a news conference at his official residence in the capital Harare after talks with his arch-rival Prime Minister Morgan Tsvangirai.

The text forms the main element of key reforms needed to hold a credible vote after discredited 2008 elections.