The summit is planned for December in Portugal. Boniface Chidyausiku, the Zimbabwean U.N. ambassador, said Brown has “no right to dictate” who should be at the meeting, the BBC reported.

Brown says Mugabe would distract attention from the issues that need to be discussed. But his threat appears to have gained little support in Africa.

President Levy Mwanawasa of Zambia said he will boycott the summit unless Mugabe is invited. Gertrude Mongella, the president of the Pan-African Parliament and a Tanzanian, said Brown’s actions would not help Zimbabwe.

"We do know there are some problems, but if somebody wants to arm-twist Zimbabwe, that's not the best way to solve the problems," she said.