The United States has criticised South Sudanese opposition leader Riek Machar for failing to return to the capital as planned on Tuesday to take oath of office.

John Kirby, the US State Department spokesperson, also announced that Troika Members — US, Britain and Norway — will consult in response to the “obstruction” of the implementation of the peace agreement.

"The United States is deeply disappointed by Riek Machar’s failure to return to South Sudan’s capital of Juba today to form the Transitional Government of National Unity. His failure to go to Juba despite efforts from the international community places the people of South Sudan at risk of further conflict and suffering, and undermines the peace agreement’s reform pillars,” said Mr Kirby.

Dr Machar failed to arrive in Juba on April 18 and 19 due to what William Ezekiel, the Sudan People’s Liberation Movement (SPLM-IO) spokesperson termed as logistical problems.

READ: Disappointment for Juba as Machar fails to return again

Mr Ezekiel later said that the government had refused to grant clearance to Dr Machar’s flight from Gambela in southern Ethiopia and that his coming has been postponed indefinitely.

Government spokesperson and Information Minister, Michel Makuei, confirmed that the government cannot clear Dr Machar to fly in heavy weapons.

The SPLM-IO claims that government had heavy weapons including tanks and helicopter gunships deployed in Luri, west of Juba and around the capital.

Meanwhile, former Botswana president Festus Mogae has called for an extraordinary stakeholders meeting in Juba on Thursday to review the implementation of the security arrangement after vice-president designate's failure to turn up.

According to Aly Verjee, the head of secretariat of the Joint Monitoring and Evaluation Commission (JMEC), the chairperson Mr Mogae has appealed to the parties to the South Sudan peace agreement to to ensure the Agreement is implemented.

“The agreement is at risk. Having come so close to the formation of the Transitional Government of National Unity, all parties must ensure that the spirit of reconciliation, compromise and dialogue embodied by the Agreement should be protected,” said the JMEC Chairperson.