Harare/Johannesburg  - Zimbabwe's opposition Movement for Democratic Change (MDC) said Tuesday that four more of its members had been killed by supporters of President Robert Mugabe in nearly a month of post-election violence that is being investigated by South African officials.

Shepherd Mushonga, an MDC MP for Mazowe Central, said four MDC members had been killed in Chiweshe, 100 kilometres north of Harare, on Sunday night after being beaten by youth militia loyal to Mugabe's Zanu-PF party.

Mushonga told Deutsche Presse-Agentur dpa that the youths went door to door looking for MDC members and that several other people had been hospitalized with injuries following the attack.

It was not possible to immediately verify the report, which the MDC says brings to 24 the number of people from within its ranks killed in revenge attacks by mainly Zanu-PF youth militia and soldiers following Mugabe's party's defeat in March parliamentary elections.

The MDC defeated Zanu-PF in the 210-seat House of Assembly. MDC leader Morgan Tsvangirai also took more votes than 84-year-old Mugabe in the presidential election, but not enough for an outright win.

The Zimbabwe Electoral Commission is expected to announce a date for a runoff between the two leading candidates in the coming days. Mugabe has said he will participate but Tsvangirai's Movement for Democratic Change, which insists he won decisively, has yet to announce whether their man will partake.

A senior MDC official told dpa Tuesday Tsvangirai would contest the runoff but that the party wanted to bring international pressure to bear on Mugabe to rein in his supporters first. The MDC claims Mugabe's supporters want to brutalize people into supporting him in a second round.

A team of South African officials led by Local Government Minister Sydney Mumafadi arrived in Zimbabwe Monday night to investigate the violence.

"They are already here and they are busy conducting wide-ranging interviews. This is not going to be a selective process. They are going to talk to all relevant players," William Geerlings, First Secretary at the South African embassy in Harare, said.

African Union were also due to discuss the Zimbabwean crisis at a two-day meeting in Tanzania's northern town of Arusha starting Tuesday, the country's foreign minister Bernard Membe confirmed.

Meanwhile, in a sign of the country's deepening economic woes, the central bank on Tuesday introduced two new bank notes - a 100 million Zimbabwe dollar note and a
250 million Zimbabwe dollar note.

The new notes come barely a month after the Reserve Bank launched what has been until now the largest single note - 50 million dollars.

With inflation now running at over 165,000 per cent, Zimbabweans get little change out of two 50 million dollars notes for a single loaf of bread. (dpa)