Juba — The head of the United Nations Mission in South Sudan (UNMISS) on Friday, expressed deep concerns on reports of threats, intimidation, and attacks against journalist, the civil society and human rights activists in the country.

Hilde Johnson, said such practices, greatly undermine people's right to enjoyment of their basic rights and freedoms of expression in society.

"UNMISS is deeply disturbed by reports of threats, intimidation, harassment and attacks against journalist, civil society and human rights activists," said Johnson at a press briefing in Juba, the South Sudan capital.

Significant efforts must now be made by the government to address this trend and to ensure that people can enjoy basic rights, such as freedom of expression, she added.

South Sudan, Reporters Without Borders said in its latest world press freedom index, ranked at 124 out of 179 countries considered.

In recent years, journalists in the new nation, which still lacks media legislation, have complained of constant harassment and intimidation, mainly in the hand of security agencies.

Last year, Ding Chan Awuol, unknown assailants gunned down a renowned South Sudanese writer and blogger at his home in Gudele, located west of the country's capital.

Two suspects, government says, have so far been arrested in connection with the killing of the writer, popularly known as Isaiah Abraham.

"...we urge the national authorities to expedite the investigation into the killing of Isaiah Abraham and bring the perpetrators to justice," said Johnson, also the Special Representative to the United Nations Secretary General.

In his new year's address, President Salva Kiir, equally expressed concern about cases of harassment, abuse and arbitrary arrests, meted against people sad to be critical of government policies.

"There are those who are being threatened allegedly for using their voices, which sometimes are critical to the government policies. They have experience harassment, abuse and arbitrary arrests. This is unacceptable. This is not what we fought for," partly read Kiir's message.

He added, "Reneging on the principles of our struggle now is disrespecting the memory of our martyrs who fought and died for our freedom".

South Sudan attained self-rule in July 2011, after its population overwhelmingly voted for separation in a self-determination vote. The plebiscite was a key part a 2005-peace deal, which ended over two decades of the north-south Sudan civil war.