New VP says Machar's time has passed

South Sudan's new vice president warned Wednesday that his predecessor and former friend Riek Machar should stay out of politics to allow peace.

Taban Deng Gai, a powerful politician and fellow member of the Nuer tribe, was a loyal ally and friend of Machar before seizing the opportunity to replace him as First Vice President after clashes in the capital Juba last month.

"Let (Machar) denounce violence, let him work for peace and let him wait for the elections in 2018," Deng said in Nairobi on Wednesday.

"It cannot be violence in 1991, violence in 1998, violence 2013 and violence again in 2016," said Deng, referring to a series of rebellions involving Machar over the years.

"I think (Machar) should have learned from those mistakes," Deng said.

The visit to Kenya -- during which Deng met with President Uhuru Kenyatta -- appeared designed to shore up Deng's position as the most senior Nuer in a so-called government of national unity established in a peace deal that has remained largely unimplemented since being signed by Machar and President Salva Kiir a year ago.

It remains unclear how much support Deng has among either the civilian Nuer population or the armed factions who have backed Machar since the start of the civil war in December 2013, many of whom see Deng's elevation as a betrayal.

"Wherever (Machar) is let him ask for a peaceful passage. If he decides to stay in the country let him stay in peace in Juba, or if he thinks he cannot stay in Juba let him come to Kenya or to any of the African countries and let him organise his political party and let him wait for the election in 2018," Deng said.

Machar's whereabouts have been unclear since last month when deadly fighting flared in Juba and led to his outgunned and outnumbered forces being chased from the city by government troops.

Deng insisted he was the man to bring peace to South Sudan, together with Kiir.

"This peace is a beautiful peace to the people of South Sudan we are not going to allow it to collapse," he said.