South Africa was at the centre of a new bid Tuesday to mediate between Zimbabwe's ruling party and opposition as more violence flared in the run-up to this month's presidential election run-off.

As the UN Security Council prepared for a special debate on Zimbabwe, South Africa's Business Day newspaper reported that representatives of President Robert Mugabe and his opposition challenger had recently gathered in Pretoria as part of a last ditch effort to draw the country back from the abyss.

According to the newspaper, South African Local Government Minister Sydney Mufamadi chaired a meeting between representatives of the opposition Movement for Democratic Change and Mugabe's ZANU-PF party at the end of May and another was planned this week.

The newspaper said Mufamadi, assisted by director-general in the presidency Frank Chikane and President Thabo Mbeki's legal advisor Mojanku Gumbi, met the three parties separately to discuss the June 27 run-off, including the possibility of shelving the ballot.

Among the suggestions put forward at the talks was the establishment of a Kenya-style government of national unity with Mugabe as president and MDC leader Morgan Tsvangirai as prime minister.

Disputed elections in Kenya led to violence in that country, only resolved when the ruling party and opposition formed a coalition government.

Mbeki was last year handed the task by his peers in the region of mediating between the MDC and ZANU-PF but his efforts have so far made little headway and Tsvangirai has called for him to be stripped of his role.

However the report said that two of Tsvangirai's key lieutenants, MDC secretary general Tendai Biti and deputy treasurer Elton Mangoma, attended the meetings in the capital Pretoria.

ZANU-PF was reportedly represented by Justice Minister Patrick Chinamasa and Social Welfare Minister Nicholas Goche.

Mbeki's spokesman Mukoni Ratshitanga confirmed that talks had taken place, saying: "That is true, yes" but refused to give further details.

"I can only say yes, the president is the mediator and he will do all that is humanly possible to ensure the success of the mediation process," he told AFP.

However MDC spokesman Nelson Chamisa denied that any such talks had taken place, saying there "is no unity government on the cards."

Levels of violence have steadily increased in the build-up to the run-off election which Tsvangirai is hoping will end Mugabe's 28-year rule of the former British colony.

According to the MDC, more than 60 of its supporters have been killed by pro-Mugabe militias since the first round of voting on March 29.

Mugabe in turn has accused the MDC of "terrorising" ZANU-PF followers, although the UN says the vast majority of victims of the spiralling violence have in fact been opposition supporters.

In the latest reported violence, the MDC accused ZANU-PF militants of stoning an opposition senator's home and torching his car in the early hours and of torching two lorries of a businessman believed to be an MDC sympathiser.

"We are now witnessing a disturbing trend of coordinated violence involving arson, assault, abductions and killing," Chamisa added.

Meanwhile state media reported that a veteran of the 1970s liberation war was killed and four ZANU-PF supporters injured by MDC followers in the southern Bikita region over the weekend when they were set on by axe-wielding MDC followers.

The government announced on Monday that suspected perpetrators or instigators of violence would now be refused bail, in a move the MDC claimed would enable Mugabe to tighten the screw on his opponents.

The vast majority of those arrested over the violence have been MDC supporters, including four lawmakers.

In a bid to create more room in the country's prisons, Chinamasa told the Herald daily that some inmates would now be freed to accommodate an expected upsurge in numbers.

"We are proposing amnesty to create space for those convicted of political violence," he told the government's mouthpiece.

"We recognise that incidents of political violence are on the increase and we want to take measures to stamp them out."