Queen Elizabeth II has opened a summit of Commonwealth leaders, where arguments over the suspension of Zimbabwe are likely to dominate talks.
Absent but on everyone's mind: Robert Mugabe
Fifty-two countries - mostly former British colonies - are represented at the conference in Abuja, Nigeria.
Zimbabwe was barred from the body in the wake of alleged election fraud by President Robert Mugabe's regime.
Mr Mugabe argues there is a white-led conspiracy against him and has threatened to withdraw from the group.
There are concerns that the Zimbabwe debate could pit wealthy, mostly white countries such as the UK and Australia against poorer African nations led by Zambia.
Some Zimbabwe supporters accuse its critics of double standards, since countries such as Australia have suggested Pakistan could be re-admitted to the organisation - though military dictatorships are not supposed to be allowed in.
Canada has signalled it is to push for a compromise over Zimbabwe's suspension.
It says it will suggest a mechanism to ensure Zimbabwe could rejoin ahead of the next summit in two years' time.
The official agenda for the conference, held every two years, ranges from the environment to poverty to HIV and Aids.
"The Commonwealth is one of the great partnerships of the world, where rich and poor, large and small, work together for the common good," the Queen said in opening the conference on Friday.
The 52 leaders at the event represent almost one-third of the countries in the world, and about 1.7 billion people.
Delegates all received a special edition of the Zimbabwe Daily News, a paper which has been shut down for its opposition to Mr Mugabe.
The paper contains "details of the violence, of the murders, of the political repression that has happened to us in Zimbabwe," editor Bill Saidi told the BBC.
Mr Saidi said he hoped Zimbabwe would not pit black against white within the Commonwealth.
"The issue here is not black and white - in Zimbabwe it's black against black," he said.
Mr Mugabe addressed the annual conference of his ruling Zanu-PF party in the central town of Masvingo as the Commonwealth summit opened.
He criticised the Commonwealth, adding there were "many other clubs to join".
UK Prime Minister Tony Blair had earlier said it was important to maintain Zimbabwe's suspension "because that sends the right signal of strong disapproval for what is happening in Zimbabwe at the
But the president of Malawi, Bakili Muluzi, has said the exclusion of Zimbabwe from the Commonwealth will hurt only Zimbabweans and not President Mugabe.
Secretary General McKinnon could face a challenge in Abuja
He said Malawi would encourage the international community to help Zimbabwe so that its people would not suffer.
On Wednesday, Zambia's President Levy Mwanawasa announced he would lead a campaign to readmit Zimbabwe.
Mr Mugabe himself blames his country's suspension from the body of 54, largely developing, states on an "Anglo-Saxon unholy alliance" of Britain, Australia and New Zealand.
Speculation is growing that some members will seek to block the re-election of Commonwealth Secretary General Don McKinnon, a New Zealander, at the summit.
But Mr McKinnon expressed confidence that his position as secretary general was secure and he played down reports that South African President Thabo Mbeki was advocating his replacement by Sri Lanka's former Foreign Minister, Lakshman Kadirgamar.
"I read in the papers, I hear about these things but I've heard nothing official," Mr McKinnon said.