The United Nations has appealed to the South Sudan authorities to release human rights defender Peter Biar Ajak from jail.
The UN said in a statement extended to the media Thursday that Mr Ajak's detention was beset with irregularities from the beginning.
"We condemn in the strongest terms Mr Ajak's continued detention and urge the South Sudanese authorities to release him immediately," read the statement.
"There is a clear trend in the use of national security and counter-terrorism legislation by states to criminalise free expression and the legitimate work of human rights defenders, in stark contradiction to their obligations under international human rights law."
Mr Ajak was arrested last year and was allegedly under investigation for treason and other purportedly national security-based offences.
He was seized at the Juba International Airport on July 28, 2018, could face the death penalty if convicted.
Mr Ajak, who is also a political commentator, is a co-founder of the South Sudan Young Leaders' Forum (SSYLF), a coalition of more than 70 young people advocating the resolution of the South Sudan conflict.
In the weeks leading up to his arrest, he had posted a number of Tweets criticising the ongoing violence and advocating change.
The UN statement said that while being taken into custody, Mr Ajak was neither informed of the reasons for his arrest, nor permitted to meet legal representatives for seven weeks.
To date, his contact with his legal representatives and his family remains sparse, said the UN statement.
"Sources say he is getting only one meal a day."
Mr Ajak was also said to be under investigation for allegedly publishing false statements prejudicial to South Sudan under Section 75 of the Penal Code, which in itself provides for a sentence of up to 20 years in prison.