UNITED NATIONS, Nov. 22 (Xinhua) -- The United Nations Security Council on Friday called on the parties to the revitalized peace agreement in South Sudan to make progress immediately in implementing the critical task of forming a transitional government.

In a statement Friday, the 15-member council said the parties failed to take the steps necessary to peacefully form a transitional government by the previously extended deadline of Nov. 12.

It voiced the concern that the parties have not made substantive progress in the implementation of the critical tasks in the pre-transitional period as were defined in the peace agreement, including transitional security arrangement and the determination of the number and boundaries of states.

In the meanwhile, the Council welcomed their agreement to establish a mechanism to supervise the task implementation.

The situation in South Sudan has led to a further extension of 100 days for forming a power-sharing government in the East-Central African country.

In early November, South Sudan's President Salva Kiir and opposition leader Riek Machar agreed to postpone forming the transitional government for an additional 100 days after failing to resolve their differences mainly on outstanding security issues.

The first extension, of six months, was agreed on in May.

South Sudan had been mired in a civil war since December 2013 between the troops loyal to Kiir and to former Vice President Machar. A peace deal signed in 2015 collapsed after renewed violence in July 2016, and the rivals signed a revitalized peace agreement in September 2018.