The spokesman for South Sudan opposition leader Dr Riek Machar, who is in exile in South Africa, has been sentenced to death after being convicted of treason and incitement against the South Sudanese government, Reuters reported.

James Gatdet Dak, who was sentenced to death on Monday by a high court in the capital Juba, was deported to South Sudan from Kenya in November 2016 in breach of international law according to the United Nations.

In addition to the death sentence Dak was also given 21 years imprisonment on charges of conspiracy and incitement against President Salva Kiir’s government.

Monyluak Alor Kuol, Dak’s former lawyer who resigned last month in protest against the case’s handling, said the sentencing violated a ceasefire signed in December, which called for the release of all prisoners and detainees.

“I am disappointed. Such trials are not supposed to take place at this time,” Kuol told Reuters.

William John Endley, a South African national who was one of Macher’s advisers, who was also charged with committing acts of conspiracy together with Dak, is to stand trial on Tuesday and a verdict is expected before the end of the month.

Machar fled to the Democratic Republic of Congo (DRC) in 2016 after clashes broke out in Juba between government forces from the Sudan People’s Liberation Army (SPLA) and his armed followers.

Shortly before fleeing, Machar had just returned to Juba from exile in the wake of the 2015 peace deal which subsequently collapsed.

South Sudan, which won independence from Sudan in 2011, descended into civil war in 2013 months after Kiir fired his deputy Machar.

Tens of thousands of people have been killed and a third of the population have fled their homes.

Despite the new ceasefire signed in December, in a new attempt to revive the 2015 peace deal, clashes have continued to break out, prompting the US to impose sanctions.

On Monday, the government accused rebels of launching attacks in the north-eastern town of Nassir.

An internationally backed ceasefire monitoring team said it was sending a team to investigate the violence in the next 24 hours.