South Sudan has temporarily abandoned registration fees for foreign and local non-governmental organizations (NGOs) in a bid to encourage groups to help with a humanitarian crisis in the country, a senior government official said.

The government and the United Nations said last month that South Sudan needed $1.7 billion in aid this year to help six million people cope with the effects of war, hunger and economic decline.

Paul Dhel, deputy chairman of the South Sudan Relief and Rehabilitation Commission, attributed the decision to waive the $3,500 fee for international NGOs, and $500 for local organizations, to the urgent humanitarian situation.

"The registration is completely for free. This is going to boost humanitarian work in the country," he told Reuters, saying the waiver would run for a year.

South Sudan has been criticized in the past for imposing massive charges on aid groups and their workers to register them to operate in the country.

The US ambassador to the UN, Nikki Haley, welcomed the waiver, but said the fees charged for work permits should also be reviewed.

"Work permit fees – often ranging between $2,000 to $4,000 per international staff member – remain a much greater financial burden," she said in a statement.

The world's youngest country has been ravaged by civil war since 2013 after clashes erupted between troops loyal to President Salva Kiir and his former deputy Riek Machar.

The rivals signed a peace deal in 2015, but that has since been ignored. A ceasefire negotiated in December was violated within hours.

On Saturday, the foreign ministers of the member states of regional IGAD (Inter-governmental Authority for Development) bloc said violations should no longer "continue with impunity", adding identified violators would be hit with sanctions like asset freezes.

The resolution will now be sent to an African Union peace and security body for endorsement, ahead of a request to the United Nations Security Council.

Members of the UN body have said that they would back measures against violators of the ceasefire.

The government in Juba was not immediately available for comment on the IGAD statement.

On Thursday, its spokesman said the ceasefire monitors were unfair and relied on second-hand information.

(Source: Reuters)