Addis Ababa - South Sudanese President Salva Kiir on Monday refused to sign a peace deal that was accepted by rebel leader Riek Machar, as the two came under strong international pressure to end their 20-month military conflict.The deal, the contents of which were not immediately known, was signed by Machar and a representative of East Africa's Intergovernmental Authority on Development (IGAD), which has overseen several rounds of talks in Addis Ababa.South Sudanese ruling party's secretary-general Pagan Amum also signed the agreement, but diplomats said he did not represent the government.Kiir only witnessed the signing of the agreement."They have certain reservations about which they have decided to go into their country and consult," said the IGAD's Seyyoum Mesfin, without explaining what the reservations were.Mesfin said Kiir would return to Addis Ababa within 15 days to "finalise the peace agreement”.Machar described the deal as a "compromise" representing "an opportunity to end the war”."I hope President Kiir will sign," he said, adding: "There is no reason why he requested more time... We call on President Kiir to reconsider his position so that they can sign and we can go forward."IGAD had set Monday as a deadline after which the warring parties would face international sanctions if they failed to strike a deal.A string of ceasefires has been unable to stop the fighting, which has killed tens of thousands and displaced about two million people.Ugandan President Yoweri Museveni and his Kenyan and Sudanese counterparts, Uhuru Kenyatta and Omar al-Bashir, had arrived in Addis Ababa to put pressure on the warring parties.Earlier talks in the Ethiopian capital had sought a power-sharing agreement and a transitional government. Several rebel commanders split from Machar recently, a move which was seen as weakening the credibility of an eventual peace deal.A power struggle between Kiir and Machar turned violent mid-December 2013, leading to ethnically based massacres and other atrocities. The European Union and the United States have already imposed sanctions on some South Sudanese military leaders.Meanwhile, in South Sudan, a heavy military presence in the streets of Juba was reported after Kiir sacked five out of a total of 10 state governors.The government did not give a reason for the sackings, but analysts said the governors may have been seen as being critical of Kiir's policies. Warrap State governor Nyandeng Malek had also been accused of cooperating with the rebels.Western Equatoria governor Joseph Bakosoro was meanwhile arrested by the army, Radio Tamazuj reported.