The United States government is obstructing peace in South Sudan, a spokesperson for rebel leader Riek Machar said.

James Gadet made the statement after US Special Envoy Donald Booth said that rebel leader and former First Vice President Riek Machar should not return to his position. Gadet said that removing Machar will lead to the collapse of the peace agreement because Machar still has a huge army and controls big parts of the country.

Weirial Pouk, a member of the armed opposition led by Machar said the US envoy's statement is not logical. Speaking to Radio Tamazuj, he said Machar being pushed away from the implementation of the peace agreement means the continuation of the war.

"The truth is that the pushing away of Machar from the government means that there is no government in South Sudan," said Pok, and added that it would mean war will continue.

Booth had said in testimony to Congress that he did not think it would be practical for Machar to return to Juba at this time. His colleague US Ambassador to the UN Samantha Power recently visited Juba at the head of a UN Security Council delegation and pledged to cooperate with the government of Salva Kiir. US Secretary of State John Kerry last month indicated US acceptance of Kiir's decision to remove Machar from power and replace him with Taban Deng Gai.

Machar was one of two main principal signatories to the South Sudanese peace deal signed in August 2015. Monitors now say most of the agreement has not been implemented.