By MacDonald Dzirutwe

HARARE (Reuters) - Zimbabwean Prime Minister Morgan Tsvangirai accused the rival party of President Robert Mugabe of planning to cheat in next week's election, and questioned the fitness of the African Union's top official to monitor it fairly.

Tsvangirai told reporters on Friday he was 'very bullish' about defeating Mugabe at his third attempt, but made clear his unease about the conduct and monitoring of the July 31 election.

The run-up has been dogged by poor planning and charges of irregularities, particularly in the electoral roll, although the African Union (AU) has described it as peaceful. The United States said last week it was 'deeply concerned' by a lack of transparency in the preparations.

Tsvangirai said he had told AU Commission head Nkosazana Dlamini-Zuma that his party had not been given access to the voter list, as required by law, and that his supporters had been intimidated by Mugabe's ZANU-PF in what he called "the militarization" of the vote.

Dlamini-Zuma had earlier told journalists that Tsvangirai's Movement for Democratic Change (MDC) had not raised major issues with her during meetings this week. Tsvangirai said her comments were misleading.

"The question would be 'Why would she want to distort a meeting in which everyone participated?' It puts into question her integrity as an impartial observer to this process," he told reporters.

"But I am very bullish about the outcome of the election. It will surprise you that despite attempts to rig, ZANU-PF will not win."

No comment was immediately available from Dlamini-Zuma.

AWKWARD TANDEM

Mugabe and Tsvangirai entered an uneasy power-sharing arrangement after the last election, in 2008, was marked by vote-rigging allegations and bloodshed.

The 89-year-old Mugabe, Zimbabwe's only leader since independence from Britain in 1980, is seeking to extend his rule despite questions over his health, allegations of human rights abuses and a disastrous economic track record.

The country is still emerging from a decade of economic decline and hyperinflation. Finance Minister Tendai Biti cut his 2013 growth forecast to 3.4 percent on Thursday and said any disputes over the election result would hit the chances of a recovery.

Tsvangirai showed journalists what he said was a used ballot paper cast by a police officer early this month, part of a bunch that had been dumped in a litter bin at a hotel being used by the Election Commission.

Tsvangirai said the officer, among 70,000 police and soldiers who took part in a two-day special vote marred by long queues, had voted for him.

"The question is how many such ballots were thrown away and what replaced them. This is yet another crude form of vote manipulation," he said.

Mugabe this week told supporters at a rally that his party "never, never" rigs elections and that the MDC allegations were mere politicking.

(Editing by Mark Trevelyan)