The opposition Movement for Democratic Change (MDC) has accused President Robert Mugabe and ZANU-PF of intimidating and attacking its supporters as part of efforts to rig the second round vote, which is due to take place by the end of July -- some four months after a disputed general election.

The government denies the charges and accuses the MDC of instigating the violence, in which the opposition says 33 of its supporters have been killed.

The state-controlled Herald daily said ZANU-PF "condemned acts of violence in the countryside and urged law enforcement agents to arrest anyone found perpetuating violence."

Justice minister and ZANU-PF spokesman Patrick Chinamasa told the paper, "We are advocating for joint MDC and ZANU-PF teams to investigate any claims of violence."

"We are interested in the truth, whether it hurts us or not. If facts show it's MDC or ZANU-PF, the perpetrators must be arrested. The judiciary must deal with any case with the seriousness it deserves. There should be no easy bail."

Zimbabwe's government announced on Wednesday it was delaying the run-off presidential poll due this month until as late as the end of July, prompting the opposition to say Mugabe was trying to buy time for a crackdown.

Opposition leader Morgan Tsvangirai, who has been abroad since shortly after the vote to seek regional support, said on Wednesday he would return home and kick off his run-off campaign in Zimbabwe's second city of Bulawayo on Sunday.

DISPUTED ELECTION

Zimbabweans voted on March 29, but results of the disputed vote were only released on May 2.

They showed Tsvangirai beat Mugabe, but not by enough votes to avoid a run-off that should have been held within 21 days of the results announcement.

In the parliamentary vote conducted the same day, ZANU-PF lost its majority to the opposition for the first time since independence from Britain in 1980. The new parliament has not yet convened.

An MDC spokesman said of the delay: "This is illegal and unfair. It is part of a programme to give Mugabe and ZANU-PF time to torment and continue a campaign of violence on the MDC."

Independent election observer group Zimbabwe Election Support Network also said any run-off held after the stipulated 21 days would be in breach of the law. It noted conditions were not conducive to a free and fair poll.

The southern African SADC grouping which will monitor the polls also said that the political environment was not yet suited for a secure and fair run-off.

SADC observed the first round of the vote in March and now says it plans to send a bigger team to the run-off. Regional states are concerned turmoil and instability in Zimbabwe could spill over and take their toll on them too.

An economic meltdown in Zimbabwe has triggered inflation of 165,000 percent, 80 percent unemployment, chronic food and fuel shortages and a flood of refugees to neighbouring states.

In the latest sign of the spiralling inflation, Zimbabwe on Thursday introduced 500 million Zimbabwe dollar notes worth just $2 -- enough to buy about two loaves of bread.