Regulator accuses reporters of lacking patriotism and acting as foreign agents.
Threatens to jail reporters for "assassination of the country and its government".
President Salva Kiir has also warned foreign envoys and media against publishing negative reports.
South Sudanese media regulator has warned journalists against what it termed as an "assassination of the country and its government".
Speaking at a forum on Freedom of Expression and Journalists' Safety held in Juba on Thursday, the director of media compliance at the South Sudan Media Authority, Mr Sapana Lado, accused reporters of fuelling the crisis in the war-torn country through biased reporting.
He said local journalists lacked patriotism and were acting as foreign agents.
“Our problem is that our journalists are acting as vendors selling South Sudan. Most of the negative reports that appear or are released by international media agencies are collected by the local media in Juba.
“You should stop assassinating the character of this country and its government,” Mr Lado told journalists.
He threatened to take reporters critical of the country and government to court.
“I wish I will still live long so that you [journalists] face the high court,” he said.
This is not the first time that the media regulator has threatened reporters.
Last year, it banned about 20 foreign journalists from entering the country on what it said was “unfounded reporting that can incite violence”.
But, Mary Ajith, the acting chairperson of the Association of Media Development in South Sudan said the comments by Mr Lado were unacceptable as they threatened the lives of journalists in the country.
She dismissed the claims that the local media was biased, saying rather that it only reported matters as they are.
“If a civil society activist tells the truth to the media, that truth is censored. But when a government official give false news, it is published. Now, who is giving fake news, the media or the government? She posed.
Lawyer and human rights activist, Mr Reech Malual, also slammed Mr Lado.
“Legally it is wrong to issue such statements which constitutes threats against journalists by a responsible official serving in the responsible arm of government. It is a hate speech,” he said.
Early this month, President Salva Kiir warned foreign envoys and media in the country against publishing negative reports about South Sudan, saying that it was hurting and delaying the restoration of peace and stability.