The United States on Monday imposed sanctions on two South Sudanese officials it accused of fomenting conflict, the U.S. Treasury Department announced on Monday, in its latest move to pressure the country’s politicians to form a unity government.

Minister of Cabinet Affairs Martin Elia Lomuro and Minister of Defense and Veteran Affairs Kuol Manyang Juuk were blacklisted for their role in perpetuating the conflict by obstructing the peace process, Treasury said in a statement.

This came even as South Sudan's government on Friday allocated $40m to speed up the integration of its soldiers with armed rebel fighters to create a unified national army – one of the provisions of a stalled peace agreement aimed at creating a power-sharing government after years of civil war.

The move reported on Friday came as President Salva Kiir and rebel leader Riek Machar held rare face-to-face talks in the capital, Juba.

South Sudan plunged into chaos in December 2013 sparked by a feud between President Kiir and Machar.

President Kiir accused Machar, his then deputy, of plotting a coup against his rule. Machar denied the allegations but then went on to mobilize a rebel force to fight the government.

The war has killed hundreds of thousands and displaced millions, making South Sudan the biggest refugee crisis in Africa.

Under the auspices of regional bloc IGAD, Sudan, Ethiopia and Kenya played key roles in mediation of the revitalized peace agreement.