NELSON Mandela, chief mediator in Burundi’s peace process, held closed-door discussions on Monday with the country’s rebel groups. The office of the former president refused to say who was attending the talks, how long the meetings would last, or where they were taking place. A spokesman said no statements would be released to the press before the end of the discussions, unless rebel groups present expressed otherwise. Mandela, who returned at the end of last week from a 10-day visit to the United States, is to meet delegations from the Burundi government, the army and groups of Hutu rebels in a four-day round of talks beginning on Tuesday, according to a Tanzanian judge and member of the mediation team.