KHARTOUM, April 3 (Reuters) - A delegation of more than 100 former rebels arrived in the Sudanese capital on Sunday to begin implementing a peace deal signed with the government in January that ended Africa's longest civil war.

James Wani head of the Sudan Peoples Liberation Movement delegation speaks to the media after arriving at Khartoum airport Sunday, April 3, 2005. (AP).

Secretary-General James Wani who heads the delegation from south Sudan is the most senior member of the Sudan People's Liberation Movement (SPLM) to go to Khartoum since the war began in 1983. It was his first visit in 21 years to the capital.

Three months of meetings will begin with thrashing out a new constitution to form the basis of a power-sharing government between Khartoum and the former rebels. Wani said meetings had already begun with leading members of the ruling National Congress Party (NCP), which dominates government and parliament.

Under the January deal the rebels and the government are to form a coalition government, decentralise power, share oil revenues and form joint military units.

The SPLM has opened six offices in Khartoum and at least 11 others around the country to register new members as it transforms into a political party from a military movement.

The SPLM were due to arrive in Khartoum soon after the signing of the deal on January 9, but were delayed because of logistical problems.

Although this puts the plan to form a new government of unity within 6 months of the deal under pressure, diplomats said the schedule was ambitious anyway and they expected a delay.

"The timeline was awfully tight and it's not surprising that there's been some slippage as both parties sort out their own structures," said one senior Western diplomat.

But Wani told Reuters the delay was due to other political forces disputing the make up of the constitutional commission and he had come to Khartoum to solve these problems. The commission should be 52 percent to the NCP and 28 to the SPLM, with other northern political forces taking 14 percent. Southern parties have 6 percent.

"This they believe is too little and this is the main reason they are not satisfied," he said. "We will engage all of them in talks." He said as soon as the percentages were agreed the commission could start work.

Once a constitution is agreed, the new government would be sworn in and SPLM leader John Garang will come to Khartoum to take up the position of first vice president. Diplomats believe this could happen as early as June or July.

Sudan's southern conflict broadly pitted the Islamist government based in Khartoum against mostly Christian or pagan southern rebels, complicated by issues of oil, ethnicity and ideology.

It claimed more than 2 million lives mostly from hunger and disease and forced at least 4 million to flee their homes.