CANADIAN Prime Minister Jean Chretien left Nigeria on Wednesday for South Africa at the end of a two-day official visit. The Canadian leader is due to attend the Commonwealth summit in Durban, starting on Friday. While in Nigeria, Chretien met President Olusegun Obasanjo and other top officials. At a joint press conference with the Nigerian leader on Tuesday, he pledged Canada’s assistance to the country’s nascent democracy. A planned joint session of Nigeria’s parliament, which the Canadian leader was to address, had to be cancelled because of a disagreement between the two houses.