South Sudan peace deal 'at risk' after Machar delayed return

South Sudan's opposition leader Riek Machar speaks during a briefing ahead of his return to South Sudan as vice president, in Ethiopia's capital Addis Ababa April 9, 2016.

Juba: Peace deal monitors in South Sudan said an unexplained delay of a rebel leader's return to the capital Juba to form a unity government with his rival President Salva Kiir was endangering an agreement aimed at ending more than two years of violence.

Riek Machar was due to arrive in Juba on Monday and sworn in as first vice president under a deal signed in August. But a spokesman for his rebel group on Monday said logistical reasons had delayed his return, causing the United States and the United Nations to express concern.