South Sudan's First Vice-President Riek Machar, a long-time rival of the country's President Salva Kiir, has been placed under house arrest, his party says.

President Salva Kiir ordered the arrest of Riek Machar, the opposition said, imperiling a 2018 peace deal. Several embassies urged their citizens to leave the country.

South Sudan’s main opposition party said its leader Riek Machar has been arrested as the U.N. called on all parties to uphold the 2018 agreement that ended the country's civil war. The U.N. had warned on Monday that the country was teetering on the edge of a renewed civil war after fighting in the north between an armed group allied to Machar and government forces.