Salva Kiir South Sudan leader urges rival to return to capital to rebuild peace

South Sudan's President Salva Kiir appealed Thursday to his rival Riek Machar to return to the capital and help rebuild the peace after a wave of deadly gun battles threatened to plunge the country back into civil war.

The whereabouts of Machar, the rebel leader who was reappointed vice president as part of a peace deal to end almost two years of bitter conflict, are not known.

"I am appealing to Dr Riek Machar to return back to Juba so that we can continue with the implementation of the peace agreement (which) ... needs the two of us to implement," Kiir said in a statement.

He said he pledged his "100 percent commitment" to ensuring Machar's security while in Juba, following the intense fighting that erupted between rival troops just as the two men were meeting in the capital on July 8.

"I will be expecting a response... within 48 hours so that we establish contact and continue building and promoting  peace amongst our people now suffering because of this uncalled-for conflict," Kiir said.

Machar has not been seen since he left Juba after days of fierce fighting that claimed the lives of at least 300 people and sent tens of thousands fleeing, many to Uganda.

The unrest in the world's youngest nation left an August 2015 peace deal hanging by a thread.

Tens of thousands of people have been killed since the war first erupted in December 2015 when Kiir accused Machar, then his vice president, of plotting a coup.

More than two million people have also been driven from their homes in the conflict, which has reignited ethnic divisions and been characterised by gross human rights abuses.