South Sudan is "on the brink of an all-out ethnic civil war which could destabilise the entire region", the head of a team of UN human rights investigators told the UN Human Rights Council, describing a shattered country where children as young as two have been raped.

In her speech to the council, Yasmin Sooka, who heads the three-member UN Commission on Human Rights in South Sudan, urged immediate deployment of a 4,000-strong regional protection force "to protect civilians all across South Sudan".

She said that the international community can stop this "Rwanda-like" genocide in South Sudan with that deployment and should also set up a court to prosecute atrocities.

"South Sudan stands on the brink of an all-out ethnic civil war, which could destabilise the entire region," Sooka said in the emergency session in Geneva on Wednesday, adding that the African Union and the government of South Sudan should immediately establish a hybrid court to prosecute human-right abuses in the country.

"Wherever we visited, people told us the country would dissolve into another Rwanda-like situation. While several of the early warning signs of mass atrocities are present, that does not mean it is inevitable. The international community must act now."

UN High Commissioner for Human Rights Zeid Ra'ad al Hussein said the African Union must quickly set up such a court "with a strong focus on command responsibility for atrocities".

Canada also called for the urgent and immediate deployment of a regional protection force, while the European Union urged all parties to allow and facilitate "the full, safe and unhindered provision of humanitarian assistance" to the country.

'Starvation, gang rape and burning of villages'

The decision to hold an emergency Human Rights Council session about South Sudan came after the UN Human Rights Commission's 10-day visit to South Sudan.

A split between South Sudan's President Salva Kiir and his former deputy Riek Machar escalated into a military conflict in December 2013, killing tens of thousands and displacing three million people.

In a report published immediately after her visit in November, Sooka said thousands of women have been raped. The economy has been crushed, she said, adding that the country has the world's highest inflation rate, at more than 800 percent in October.

"There is already a steady process of ethnic cleansing under way in several areas of South Sudan using starvation, gang rape and the burning of villages," Sooka said 

READ MORE: South Sudan denies UN allegations of 'ethnic cleansing'

Machar and Kiir signed a peace deal in August 2015 and formed a unity government in April this year, but that did not stop the fighting.

The government responded to the United Nation's latest allegations and suggestions by saying that "these allegations were attempts to tarnish its reputation, its image with the international community", according to Al Jazeera's Hiba Morgan, who was reporting from Juba.

"The president spoke to the parliament of South Sudan today and he said he hopes the international community will stop tarnishing the image of the country," she said.

Kiir has denied there is any ethnic cleansing. In the speech, Kiir also called for a national dialogue that would attempt to redefine the country's national identity.

He called for a ceasefire in the civil war but offered few details on how it would work with multiple opposition groups across the country.

"I am calling upon all of you to forgive one another," he said. 

Kiir said a panel of "eminent personalities and people of consensus" would guide a national dialogue which would involve "all the people of South Sudan" but did not say who the panel members would be.

"As long as I am your president, I will not allow the suffering of our people to continue and I will not also allow this country to fall apart," Kiir said.