Delegations from 162 countries, gathered in Rome to seek ways out of a global food crisis, will be addressed today by President Mugabe of Zimbabwe. This statement is true in every detail - and yet absurd. Mr Mugabe has long experience of inflicting hunger, but none of relieving it.

For the UN Food and Agriculture Organisation (FAO) to offer him its most influential podium at a time of acute international anxiety over food prices and shortages might, conceivably, expose him to the sort of forthright criticism from which he is insulated at home. More likely, it will expose the FAO to the charge of self-parody.

The organisers of the world food summit cannot be faulted for their timing. Soaring world prices of wheat, meat and dairy produce may galvanise some of the 50 heads of state attending into co-operative action. Signs of flexibility at the Doha Round of world trade talks may bring progress on cutting subsidies that impede poor farmers' access to world markets. Mr Mugabe's presence, though, is an insult to the UN and the world. The problems being addressed in Rome are global. Zimbabwe's are local, man-made and the sole responsibility of its leader for the past 21 years, whose arrival in Rome on Sunday night surprised protesters (who were waiting for President Ahmadinejad of Iran) but not police, who gave him and his substantial entourage an escort to their hotel. On Mr Mugabe's watch in Harare, Zimbabwe's wheat production has fallen by 90 per cent. Its maize harvest has fallen by three quarters. Most of its children suffer severe protein deficiency while most of its farmland lies fallow: the country on which sub-Saharan Africa relied for cereals until a decade ago has just imported 600,000 tonnes of maize.

If Mr Mugabe's last visit to the FAO in Rome is any guide, his wife will take full advantage of the shopping opportunities while his people subsist in the wreckage of hyperinflation. This time, Zimbabweans are also enduring the beatings and intimidation of Zanu (PF) “war veterans” preparing the electorate for a second round of presidential voting this month that they hope will reverse Morgan Tsvangirai's first-round victory in April. Such misrule has left Mr Mugabe and his ministers subject to a ban on travel to the EU. He has been able to circumvent this ban because the summit is a UN event (see page 18); because Zimbabwe, as a UN member, has a sovereign right to choose its own delegates; and because he is immune as a serving head of state from prosecution under international law.

But for this immunity, evidence emerging from Zimbabwe might well support a prosecution of its leader under the UN Convention on Torture - the instrument that underpinned the arrest and trial of the former Chilean President Augusto Pinochet. This evidence will not go to waste. It is being collected by prosecutors in several jurisdictions, including the UK, for use in a potential prosecution of Mr Mugabe - should he ever stand down - or of his henchmen.

The FAO has failed to condemn Mr Mugabe or to regret his attendance at the summit, which Australia and Britain have called obscene. A spokesman drew parallels with US protests at Fidel Castro's regular appearances at the UN in New York. A more apt parallel would be with Jean-Pierre Bemba, the former Congolese Vice-President, arrested last week in Brussels on a warrant from the International Court of Justice. Such warrants are not lightly issued; nor should they be. Uncontrolled abuse of international law would be the result, with frivolous warrants to match every ill-researched grudge. But there is nothing frivolous about the move to hold Mr Mugabe and his aides accountable. The Zimbabwean President is making a mockery of the UN and its food summit, even as his people starve.