JUBA, South Sudan (AP) —

A prominent South Sudan activist and economist was freed from prison Saturday after a presidential pardon and said he will return to his work to ensure peace goes forward in the country after years of civil war.

Peter Biar Ajak in a brief statement to reporters said his detention had been “extremely harsh” but improved before the release. He said a medical check-up was a priority after poor health treatment behind bars.

Human rights groups and others had protested Ajak’s arrest in 2018 without government explanation. He was sentenced to two years in prison last year after being accused of inciting an uprising behind bars and threatening the security of the state.

The presidential pardon for some 30 inmates was announced Thursday evening. Friends and family waited in vain Friday for the release while South Sudan’s justice and interior ministries were processing the order.

Ajak’s father, Ajak Deng Biar, joined his son in expressing happiness at the release. The father added that he was thankful to President Salva Kiir.

South Sudan was meant to free all political prisoners under a peace deal signed in September 2018 to end its five-year civil war that killed almost 400,000 people.

The crucial next step in the peace deal, the formation of a coalition government between Kiir and armed opposition leader Riek Machar, was delayed for 100 days in November to the dismay of some observers.

The United States and others have expressed hope that the current deadline will be met.