African leaders, preparing for a summit in Lisbon with the European Union this weekend, have criticised Gordon Brown's decision to boycott the meeting because Robert Mugabe is attending. Zimbabwe, they said, was not the main issue, and Britain should have joined its EU partners in planning a new “partnership” with Africa. Even the Portuguese hosts grumbled that the focus should be on trade, migration, energy and good governance rather than on President Mugabe.

Their protests are absurd. The presence at the summit of a dictator who has reduced a once wealthy country to penury, hunger and humiliation makes a mockery of all talk about a “fresh start” in relations. What Mr Mugabe has done to his country has blighted Africa's development and fuelled widespread cynicism over its will or ability to combat endemic corruption, cronyism, economic incompetence and political malice. What is so deeply depressing is that not only African leaders are defending the man whose policies have driven millions of his people into exile and turned a former breadbasket into a basket case; even some European leaders appear to think the Prime Minister's refusal to sit down together with Mr Mugabe is nothing more than a petty spat between a former colonial ruler and an African leader angered by the slow pace of land reform.

Africa does indeed need to work out a comprehensive new framework of relations with Europe: one in which its failings are frankly acknowledged and commitments are given to the minimum degree of democracy, security and governance that would allow the EU to boost trade and raise infrastructure aid from £1.85 billion over the past five years to £2.77 billion over the next five. How can the necessary frank discussion be held with the 48 African leaders present when none is ready to speak out against the kind of cruel and blinkered policies in Zimbabwe that are the cause of the country's suffering? As long as they prefer to salute Mr Mugabe as a veteran “anti-imperialist” rather than tell him to his face that he is an embarrassment, their demands for better trade and aid deals with Europe carry little weight. South Africa, the powerhouse of the continent, carries a particular responsibility. Not only was it the main proponent of the vaunted — and failed — New Economic Partnership for Africa (Nepad); but it has, by its refusal to condemn Mr Mugabe or put pressure on its neighbour, allowed him to indulge his megalomania. Whoever succeeds President Mbeki must rethink the short-sighted indulgence that has neither halted the ruin of Zimbabwe or the outflow of refugees nor prompted regime change that a cut-off in energy supplies would surely hasten.

Mr Mugabe will be delighted by Mr Brown's absence. He can crow to fellow Africans that it is Britain's obstinacy that has caused Zimbabwe's problems and make much of his resistance to the “forces of colonialism”. Too many may still fall for such arrant nonsense. And those who see through the charade may find it politic to keep silent about failings all too familiar in their own entourage. The EU has no excuse. Having disgracefully allowed Mr Mugabe to attend, it must use this weekend to point out his cruelty and crimes, in public, to others. Only then can it start seriously discussing a new relationship with Africa.