Ululations and cheers rang out as one by one, representatives from the transitional government and rebel groups signed the deal, a year after the peace talks began, at a ceremony in the South Sudanese capital Juba.

"Today we have reached a peace agreement. We are happy. We have finished the mission," Tut Gatluak, head of the South Sudanese mediating team said shortly before the signing took place.

Ending Sudan's internal conflicts has been a top priority of the transitional government, in power since last year's ouster of longtime dictator Omar al-Bashir in a popular pro-democracy uprising.

Sudanese paramilitary commander Mohamed Hamdan Daglo -- best known by his nickname "Hemeti" -- signed the deal on behalf of Khartoum.

A representative of the Sudan Revolutionary Front (SRF) and others from the groups making up the coalition, also signed.

The SRF comprises rebel groups from the war-ravaged western Darfur region, as well as the southern states of Blue Nile and South Kordofan.

Guarantors of the deal from Chad, Qatar, Egypt, the African Union, European Union and United Nations also put their names to the agreement.

The deal covers a number of tricky issues, from land ownership, reparations and compensation to wealth and power sharing and the return of refugees and internally displaced people.

However two other powerful rebel groups did not sign, reflecting the challenges still facing the peace process.

- 'An historic day' -

Sudan has been torn by multiple conflicts between the Arab-dominated government that was led by Bashir for three decades and rebels drawn from non-Arab ethnic groups in its far-flung regions.

In Sudan's vast rural areas, settled ethnic minority farmers have frequently competed for scarce resources with Arab herders, who have often been backed by Khartoum.

Multiple civil wars have raged since independence in 1956, including the 1983-2005 war that led to the secession of the south.

The devastating war in Darfur from 2003 left at least 300,000 people dead and 2.5 million displaced in its early years, according to the UN.

"This signing means we left the war now behind us. This agreement means democracy, justice, it means freedom in Sudan so we are very happy... by this peace agreement the economy in Sudan will boom again," Ismail Jalab, a senior member of the SRF told AFP.

The peace talks were mediated by South Sudan whose leaders themselves battled Khartoum as rebels for decades before achieving independence in 2011 and who are still struggling to bring peace to their own country.

The final signing ceremony was held at the John Garang Mausoleum in Juba, the final resting place of the late leader of the independence war.

Entertainers from South Sudan and Sudan performed for thousands of guests, many of them Sudanese refugees.

"This is a very historic day to us Sudanese because this peace is going to end the protracted conflict ... it is well known since independence of Sudan there is no stability, there is no social economic development because of marginalisation," said 32-year-old Abdal Aziz who fled Darfur six years ago and has been living as a refugee in South Sudan.

- 'Challenges and pitfalls' -

Sudan's leaders, including Prime Minister Abdalla Hamdok, head of the transitional sovereign council General Abdel Fattah al-Burhan and General Hamdan Dagalo, deputy chief of Sudan's joint military-civilian sovereign council, attended the ceremony.

Heads of state from Ethiopia, Somalia, Djibouti and Chad were also there.

Upon his arrival, Hamdok said that "peace will open broad horizons for development, progress and prosperity.

"The peace building process faces various challenges and pitfalls that we can overcome through concerted efforts and joint action," he said.

Mini Arko Minawi, leader of the Sudan Liberation Movement which is a member of the SRF, said Sudan's troubled economy and "fragile political situation" were tests facing the agreement.

The economy has suffered from the country's inclusion on Washington's terror blacklist, decades-long US sanctions and the 2011 secession of the country' oil-rich south which deprived the north of three-quarters of its oil reserves.

Economic hardship triggered the anti-Bashir protests and remain a pressing concern -- food prices have tripled in the past year and the Sudanese pound has depreciated dramatically.

One of the holdout groups, the Darfur-based Sudan Liberation Movement (SLM) faction led by Abdelwahid Nour, launched an attack on Monday, the army said.

Another, the South Kordofan-based wing of the Sudan People's Liberation Movement-North (SPLM-N) led by Abdelaziz al-Hilu, has signed a separate ceasefire.