Exiled opposition leader Riek Machar has arrived in Juba for meetings with President Salva Kiir and members of the UN Security Council.

The expected talks in Juba are seen as an important step towards discussing challenges facing the revitalised peace deal. The key areas to be discussed this weekend include the implementation of security arrangements, the number of states and their internal boundaries.

Machar's return to Juba, the second in less than two months, comes amid international pressure before a November 12 deadline to form a unity government, a key part of the peace deal signed by the rival parties in September last year.

Machar, who lives in Khartoum, landed in the capital in a Sudanese plane.

Mr. Machar, accompanied by a large delegation of members of his SPLM-IO, was received by government officials at Juba airport.

"Dr. Machar would meet with President Salva Kiir and there will be another meeting with a delegation of members of the UN Security Council and members of the AU Peace and Security Council," SPLM-IO's deputy spokesman, Manawa Gatkuoth Gual, said.

"The meeting aims at discussing the outstanding issues related to the implementation of the peace agreement, especially the security arrangements and the issue of states and boundaries," he added.

Tut Gatluak, presidential security advisor and head of the National Pre-Transitional Committee (NPTC) said Machar's visit to Juba aims at discussing outstanding issues in the peace agreement.

"We are happy to receive Dr. Riek Machar. He has come to Juba to take part in meetings because members of the UN Security Council and AU Peace and Security Council are coming to Juba," he said.

 The top government official reiterated their commitment to peace and stability in South Sudan. "We want to assure the public that the leadership will work to find solutions to the critical pending tasks," he said.

A South Sudanese civil society organisation called on all parties to the peace deal to hold fruitful talks to ensure peace prevails in the country, and urged them to make compromises on critical pending issues in the peace deal.

"Excellent politicians are known for making political compromises, reaching political consensus and availing political will for the best interest of their nation without external pressure," said Edmund Yakani, executive director of Community Empowerment for Progress Organisation, a national nonprofit.

The revitalised peace deal brokered by the East African bloc IGAD reinstates opposition leader Riek Machar as first vice-president, one of five vice-presidents.

A similar peace deal, that returned Machar to the post of first vice president, was signed in 2015 but fell apart a year later.