South Sudan's rival leaders should "honour" Pope Francis' legacy by ending the country's conflict, the Vatican's diplomatic representative to the nation has said.

"We must try to make concrete in the daily life of South Sudan his ardent wish to see a true, durable peace, to see dialogue as the condition of that peace and to see the silencing of the weapons of war," Archbishop Séamus Patrick Horgan said.

The Pope, who died aged 88 on Monday, had urged the two sides of South Sudan's conflict to forge a permanent peace during a historic trip to the east African nation in 2023.

Recent violence has threatened to end a fragile peace agreement struck in 2018 between the civil war's two factions.

The head of the UN mission in South Sudan, Nicolas Haysom, recently warned that the country was "on the brink of a return to full-scale civil war".

Tensions rose at the start of March, when a militia group allied to Vice-President Riek Machar during South Sudan's civil war clashed with the army.

Archbishop Horgan said Pope Francis "spoke firmly" during his 2023 visit, calling for "no more bloodshed, no more conflict, no more violence", adding that the late pontiff's message was still "relevant".

The Archbishop, who spoke to congregants attending Mass at St Theresa's Cathedral in the capital, Juba, on Friday, said it was "disheartening" to see continuing reports of violence.

The same day, the United Nations Mission in South Sudan (Unmiss) called for an end to the clashes in the country after reports of fighting between the Sudan People's Liberation Army In Opposition (SPLM-IO) and South Sudan People's Defence Forces.

Meanwhile, Machar, who leads the SPLM-IO, remains under house arrest, facing accusations of trying to spark a rebellion.

Shortly after South Sudan's birth in 2011, the country descended into civil war between supporters of Machar and President Salva Kiir.

Archbishop Horgan reminded congregants that South Sudan held a special place in the Pope's heart, outlining his "extraordinary relationship" with the country and "affection" for the people.

The Mass was also attended by Kiir and Vice-President Taban Deng Gai – two of the four South Sudanese leaders – whose feet were kissed by Pope Francis in the Vatican in 2019.

Speaking at the end of the Mass, Kiir said: "As an icon of peace, tolerance, forgiveness, reconciliation, harmony and inclusivity, Pope Francis' message resonated with the people of all faiths all over the world."

However, Christian faithful who attended the Mass said they were disappointed that the president did not use the opportunity to re-commit to peace, reconciliation and dialogue.

Justin Badi Arama, the Archbishop of the Episcopal Church of South Sudan (ECSS) and the Anglican Primate, who took part in the prayer service, said: "It is sad that Pope Francis has passed on when the Revitalised Peace Agreement is seriously sick.

"As we celebrate his passing on today, we call upon the transitional government of national unity to make every effort to make sure that the revitalised agreement, which is seriously sick, does not die."

The Auxiliary Bishop of the Catholic Archdiocese of Juba, Santo Loku Pio, said the leaders of South Sudan chose to ignore Pope Francis' iconic "simplicity and gesture" in Rome in 2019, when he knelt down and kissed their feet in a humble plea for peace, unity and reconciliation.

He said the gesture by the Pope remained "deeply moving".

Bishop Loku added that Pope Francis wanted to make South Sudan a nation that understood the urgency for peace, unity and reconciliation, but that the leaders of the country ignored his efforts.

Ambassadors, religious leaders from other Christian denominations, and representatives of Muslim community also attended the prayer service.