Addis Ababa - South Sudan's rebel leader Riek Machar accused government forces on Monday of repeatedly breaking a ceasefire and putting at risk a peace deal just days after it was reached.
President Salva Kiir signed the peace pact on Wednesday, but even as he did so he accused rebels of attacking his forces. The UN Security Council has warned both sides that it could impose sanctions if the deal collapses.
"There is danger that is looming that could wreck this peace agreement now," Machar told Reuters in an interview in the Ethiopian capital Addis Ababa.
Accusing government forces of attacking rebel positions, he said: "We believe that this is an act that is a serious violation to the ceasefire because what it does is provoke our troops that are in control of these areas."
Machar is expected to become first vice president during a three-year transitional period envisaged by the peace deal that aims to end 20 months of conflict in the world's newest nation.
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The conflict erupted in December 2013 after a power struggle between Kiir and Machar, his former deputy. Fighting has reopened ethnic fault lines between Kiir's Dinka and Machar's Nuer clan.
Thousands of people have been killed and more than 2.2 million driven from their homes, many fleeing to neighbouring states. Many in the nation of 11 million people depend on food aid to survive.
Machar said government troops and their fleet of gunboats mounted with heavy artillery were encroaching further into rebel-held territory in oil-rich Unity state.
A government spokesperson could not immediately be reached for comment.
On Saturday, the insurgents said their positions in Adok, a port in Unity state, and around Malakal, further east, came under assault by government troops, charges Juba denied.