Zimbabwe says it is leaving the Commonwealth after the organisation extended its suspension of the southern African country for violating its democratic principles.
President Robert Mugabe's information minister said the suspension, renewed at a summit on Sunday in Nigeria, proved that "racist leaders in Britain and Australia" had taken over the group, whose members are mainly former British colonies.
Talks on Zimbabwe had dominated a four-day Commonwealth summit in the Nigerian capital Abuja, causing the worst split since South Africa's apartheid in the 1970s and 1980s and dividing its 54 members largely on colour lines.
Zimbabwe was suspended early last year on the grounds that Mr Mugabe, who has ruled the country since independence in 1980, rigged his re-election in 2002 and persecuted his opponents.
Some African Commonwealth members lobbied hard for its readmission but failed to win the day.
British Prime Minister Tony Blair, who had led the drive to keep Harare suspended, said it would send "a clear message to people in Zimbabwe that the Commonwealth is on the side of democracy and human rights".
There was no immediate British reaction to Zimbabwe's decision to quit the Commonwealth - which gives its members a political stage and some trade benefits - for good.
The government in Harare said the leaders of Jamaica, Nigeria and South Africa called Mr Mugabe on Sunday to urge him not to pull out, but to no avail.
"Our problem with Britain and Australia is over the land we took over from their white kith and kin to redistribute to the indigenous black people of this country," Zimbabwe Information Minister Jonathan Moyo told Reuters. "These racist leaders are using the Commonwealth to try to punish us."
Mr Mugabe accuses Britain and its allies of punishing him for land reforms that have given white-owned farms to landless blacks, an argument that finds resonance with other Africans.