Ceasefire declared after deadly South Sudan clashes

South Sudan's president and his estranged deputy ordered a ceasefire on Monday after a new day of heavy fighting in the capital that sent thousands fleeing and threatened a return to civil war.

President Salva Kiir's ceasefire order on Monday evening was followed by a similar call from ex-rebel and Vice President Riek Machar, raising hopes of an end to three days of deadly fighting between the army and former rebels in the world's youngest nation.

UN Secretary General Ban Ki-moon meanwhile called for an immediate arms embargo against South Sudan and also appealed to the UN Security Council for targeted sanctions against those involved in the fighting.

The UN mission in South Sudan (UNMISS) should also be strengthened with attack helicopters, Ban said.