Yesterday, Mbeki did it again. When he was asked about the 77 ton shipload of Chinese weapons in the Durban Harbour destined for Zimbabwe , he replied: "What weapons? I think you should ask the Chinese. There might be a consignment of coal that is being exported to the Congo or something. It is a port, those weapons would have had nothing to do with South Africa."

His response to the Zimbabwe crisis typifies the denialism and ‘do-nothingism' that has become the hallmark of his Presidency. It echoes his now infamous denial of the Aids pandemic and his response to the growing narcotics crisis in South Africa . "What is Tik?" he asked at an imbizo last year.

It also reflects his view on crime, which many South Africans regard as the biggest crisis of all. "Nobody can prove," said Mbeki, "that the majority of the country's 40 to 50 million citizens think that crime is spinning out of control". Similarly, in 2006, when challenged about South Africa 's electricity generation capacity, he responded "There is no crisis....whatever needs to be done...is being done".

Mbeki's capacity for denial is his greatest failing as a leader, and it will define his legacy. It is an even greater failing than the other hallmark of his Presidency, the growth of racial nationalism. Denialism will eclipse his considerable contributions in the arena of macro-economic policy.

Mbeki's instinct is to deny a problem and do nothing, until he is forced to apply retrospective crisis management. His insistence that a "normal electoral process" has been followed in Zimbabwe , is a classic example of this pattern.

There is nothing "normal" about the "recount" due to take place in 23 constituencies tomorrow, when the results of the original count have not been released. Does anybody in their right mind believe that the "recount" will not be used as an opportunity to stuff ballot boxes with votes for Mugabe in the names of some of the estimated 3 million "ghost names" on the voters roll?

At the UN Security Council on Wednesday, Mbeki dodged the Zimbabwe question until he was pressed on the issue. He then simply repeated his assurance that the situation was manageable.

Yesterday, instead of moving swiftly to halt the transport of the Chinese arms through South Africa en route to Zimbabwe , Mbeki's Cabinet did nothing. This was because, in the words of Cabinet Secretary Themba Maseko, we have to "tread very carefully" in relations with our neighbour.

Why? For fear of upsetting Robert Mugabe, who is no doubt preparing for the next phase of the intimidation campaign he is already waging against opposition supporters as he tries to force a presidential run-off election?

Transporting the arms across South African territory to Zimbabwe is illegal under certain circumstances. In terms of the National Conventional Arms Control Act, anyone who conveys, freights or transfers weapons is required to apply for a conveyance permit that can only be granted only by the National Conventional Arms Control Committee (NCACC) after consideration of how those weapons will be used.

The law clearly states that the NCACC must not allow the transfer of arms to governments that suppress human rights. It prohibits the conveyance of weapons to countries where the weapons are likely to escalate conflict and endanger peace. Zimbabwe fits the bill on both counts.

It is encouraging that the South African Transport and Allied Workers Union is reportedly refusing to off-load or transport the weapons cargo. The DA has today called on the Chairperson of the NCACC, Sydney Mufamadi, to immediately suspend the permit and to explain how it was granted in the first place.

If neither Mufamadi nor Mbeki intervene, they could be complicit in state-sponsored terror of genocidal proportions. It is worth remembering that it was a consignment of Chinese machetes that prefaced the killing of 800,000 people in Rwanda in 1994. [1]

The mind boggles when one considers the damage that could be done with the consignment of rocket launchers, grenades and semi-automatic weapons that are sitting in the Durban harbour.

Mbeki's denial and do-nothingism infects government office-bearers across the board. When I was in New York last week, I met with our Ambassador to the United Nations, Dumisani Kumalo. I urged him to use South Africa 's position as rotational Chair of the Security Council to address the crisis in Zimbabwe .

It was clear from our interview that, true to the President's policy, Kumalo had no intention of putting Zimbabwe on the agenda. He called it an "internal matter" - despite the devastating implications the Zimbabwe crisis has for the whole sub-continent. He told me he was unable to influence the agenda of the Security Council. In fact, the truth seems to be somewhat different. South Africa has, in fact, resisted calls by numerous countries to raise the topic; it was only after the intervention of UN Secretary-General Ban Ki-Moon that Zimbabwe was put up for discussion.

Mbeki's denialism is a flaw of tragic proportions, and its cost to the region and South Africa is incalculable. If he had faced the grim reality of the AIDS pandemic from the outset, millions of lives could have been saved. If he had recognized and confronted the reality of the emerging dictatorship in Zimbabwe , he could have played a role in preventing the systematic abuse of human rights which has seen thousands beaten up and murdered.

President Mbeki has forfeited his carefully honed legacy as the chief proponent of the African Renaissance. Rather than the statesman who advanced good governance and democratic practice in Africa, he will be remembered as Mugabe's junior partner - the Mussolini to Mugabe's Hitler - in the brutal oppression of the people of Zimbabwe .

It is ironic that Mbeki's actions - or lack of action - feed the negative stereotype of Africa that he has sought to dispel. The damage done to South Africa 's international image as an emerging viable democracy will take years to reverse.

This, the lowest ebb of Mbeki's tenure, will be long remembered. Those hands clasped across the tarmac, and the denial and do-nothingism they symbolise, will remain the defining image of Thabo Mbeki's Presidency.

This article was published in South Africa Today, a weekly letter by the leader of the Democratic Alliance, Helen Zille, April 18 2008