Zimbabwe's main opposition leader Nelson Chamisa made a veiled threat on Wednesday to boycott elections on July 30 if there is no agreement between the independent election agency and political parties on ballot papers.

Chamisa and his Movement for Democratic Change (MDC) are the main rivals to President Emmerson Mnangagwa in the first presidential and parliamentary vote since Robert Mugabe resigned last November following an army coup.

The MDC is wary of any attempt to put it at a disadvantage to Mnangagwa and the ruling ZANU-PF party, insisting there be a deal on how to design, print and store ballot papers.

Chamisa said his party rejected the papers being printed by the Zimbabwe Electoral Commission (ZEC).

"We do not and will not accept the current ballot paper that has been printed without our participation," he told reporters.

Asked whether he would boycott the polls if ZEC ignored his party's demands, Chamisa said: "There will be no election, there can't be an election. Choose what to call it, but there can't be an election."

He would not reveal how the MDC could stop the vote, in which 23 candidates are running for president, but added that the opposition would not "repeat the mistakes of 2013" when it suffered a crushing defeat.

The MDC called Mugabe's victory five years ago a monumental fraud that had been engineered through manipulation of the voters' register by state security agents.

ZEC chief Priscilla Chigumba said her commission alone was empowered to deal with the issue of ballot papers, and demands by the MDC were meant to usurp its powers.

Presidential and parliamentary ballots were being produced by the central bank's printing arm Fidelity Printers, she added in a statement.

An MDC official said the party had notified police it would demonstrate next Wednesday to press its demands. Thousands of MDC supporters marched to the ZEC offices on June 5, demanding reforms that the party said were vital for a credible vote.

Zimbabwe Defence Forces spokesperson Colonel Overson Mugwisi separately rejected MDC allegations that soldiers had been deployed in rural areas to campaign for ZANU-PF and intimidate opponents.