The Dec 8-9 summit in Lisbon will be the first between the two continents in seven years. Previous efforts to meet have stumbled over whether Mugabe, whom the West accuses of widespread human rights violations, could be invited.

EU president Portugal has said Mugabe will be invited this time -- despite threats of a British boycott -- and had been working on finding a way to alleviate the concerns of EU states opposed to inviting him.

An EU official said Britain, Sweden and the Netherlands had insisted on "a real discussion on human rights and governance in Zimbabwe"

"We will organise a debate (at the summit) so that he can receive a clear and tough message," the official said after foreign ministers discussed the summit on Monday.

A spokesman for the Portuguese EU presidency declined to say what that message might be.

Britain has for years led opposition to inviting Mugabe to EU summits, and Prime Minister Gordon Brown has said he would not attend the Lisbon summit if Mugabe shows up.

A British official said London has pushed the EU to give a strong message on human rights, but Monday's agreement to do so would not change the plan to boycott the summit if Mugabe comes.

"The message from the prime minister was clear, neither he nor any senior official will attend if Mugabe does," the official said, adding that raising concerns at the summit was the least the EU could do.

African leaders see the Zimbabwean president as an independence hero but Western critics accuse him of ruining the economy, rigging elections and violently suppressing opposition.

The Czech Republic has also said boycotting the summit was an option, while the EU Nordic countries renewed calls last month for Mugabe not to come.

Denmark's Prime Minister Anders Fogh Rasmussen has said he could only attend if human rights in Zimbabwe were discussed.

The EU has imposed sanctions on Mugabe's government, including a visa ban on top officials, which can be lifted for Mugabe to attend the meeting.

Mugabe denies he has wrecked the economy with policies such as seizing white-owned farms for blacks with little experience, and he blames Western pressure for hyperinflation and hunger.

Zimbabwe delayed on Monday the release of inflation data and said it might not be available "for a while", fuelling concerns the government had failed to hold back runaway prices.

The 27-member EU is Africa's largest trading partner with trade totalling more than 200 billion euros last year.