JUBA, Sudan – South Sudan's former rebels warned on Sunday that leading party members must not contest seats in upcoming elections as independent candidates, and issued a deadline for them to withdraw.

The south?s ruling Sudan Peoples? Liberation Movement (SPLM) is challenging its former civil war enemies in the north in the first elections in 24 years due in April.

However, several influential figures not selected as official SPLM candidates have stepped forward to stand as independents for key governor posts.

"We ask them to maintain the unity of the party by not contesting, but rather to endorse the official SPLM candidates," SPLM secretary general Pagan Amum told reporters in the southern capital.

"We really do not want a situation where the party divides itself on issues of power struggle."

In oil-rich Unity state, junior oil minister Angelina Teny -- wife of the south?s vice-president and SPLM deputy chairman Riek Machar -- is standing for governor as an independent.

Presidential adviser Alfred Gorre is challenging the SPLM candidate for Central Equatoria, while Aleisio Ojetuk, current governor of Eastern Equatoria, is standing as an independent after the SPLM chose a new candidate.

Amum said that SPLM members standing as independents must withdraw their names by February 13, the day election campaigning officially begins.

"By 13 February we will expect them to withdraw their candidature and not to proceed to elections," he said.

"After that, we will make our position clear if there are some who refuse," he added, without elaborating.

There are concerns the election contests could boost tension in regions already struggling because of bloody inter-ethnic clashes.

In 2009, some 2,500 people were killed in south Sudan and 350,000 fled their homes -- a higher death toll than in the troubled western region of Darfur.

The elections were provided for in the Comprehensive Peace Agreement (CPA), signed in 2005 between north and south Sudan to end a devastating 22-year civil war that cost the lives of two million people.

The CPA is also meant to pave the way for a referendum on southern independence in January 2011.

Yassir Arman, a secular Muslim from northern Sudan, was chosen to fight Omar al-Beshir in the presidential election, the first multi-party ballot since 1986 in the African continent's largest state.

For the presidential election of semi-autonomous south Sudan, the SPLM chose the current president of the region Salva Kiir, a former rebel commander who is also first vice president of all Sudan. - AFP