The Sudan People's Liberation Movement (SPLM) has named a northern Muslim, Yasir Arman, as its candidate for the April presidential elections.

Arman is a mid-ranking 20-year veteran of the SPLM and heads the party's parliamentary group. He will face Sudanese President Omar Hassan al-Bashir in the elections - the country's first in 24 years following a civil war that ended five years ago. The conflict was Africa's longest and claimed some two million lives.

The SPLM's stronghold in southern Sudan is to hold a referendum on independence next year and the oil-rich region is expected to choose secession. By naming Arman instead of party leader Salva Kiir as its candidate in the presidential elections, some observers believe that the SPLM has already effectively voted against unification with the north.

Kiir is to run in April's elections for re-election as president of the already semi-autonomous south, which is largely Christian and animist.

However, other observers see the choice of Arman as a strategic move to gain votes in the Muslim north to give the SPLM a better chance of leading a unified Sudan.

Reuters quoted Pagan Amum, SPLM secretary general, as saying: "We want Kiir to continue being the president of the south to take the people of the south to the referendum … Yasir Arman is a long-term SPLM cadre and a capable leader and our best candidate."

The former head of the SPLM, John Garang, supported unification and said he wanted to end marginalisation and discrimination across Sudan. He died in a helicopter crash shortly after the peace agreement was signed between the north and south in 2005.

Bashir was nominated for the presidency by the ruling National Congress Party last week after announcing his retirement from the Sudanese military. Sadiq al Mahdi from the Umma Party is also contesting the elections. Islamist Hassan al-Turabi's party has nominated a southerner.