A south Sudan minister has been shot dead in an apparent personal dispute, the southern army has announced.

Jimmy Lemi Milla - and his bodyguard - were killed after an attacker broke into his parked car in Juba, stole his bodyguard's gun, and shot the minister of cooperatives and rural development several times in his office, witnesses reported.

"He shot the minister with two shots to the forehead, two in the shoulders and one in the arm. He died immediately," Thomas Wani Kondo, an MP with the south's ruling SPLM movement, said.

The killer then shot and killed 62-year-old Lemi's bodyguard, before being wrestled to the ground and taken into custody.

The attacker was Lemi's brother-in-law - and wanted to claim two months' unpaid wages, officials said, dismissing any political motive to the killing.

Secession vote

The incident comes just two days after results of a referendum on south Sudan's secession from the north prompted wild celebrations in the city on the White Nile- which will become the capital of the world's newest country, when the state of Southern Sudan is created on July 9.

"This is such a shock to the people here, coming so soon after our peaceful referendum," Richard Lukodu, a civil servant, said.

"This is something for which I cannot express my sadness. This is the result of one angry man - and people should not think that this is reflective of all of south Sudan."

The situation remains under control, officials said.

"But it is a very sad day for the people of south Sudan," a spokesman for the southern army said.

The south fought a decades-long civil war against Sudan's north which ended with a 2005 peace deal, although violence in the south remains persistent. An estimated 3,000 people were killed in ethnic battles and cattle raids in 2009 alone, yet attacks had diminished ahead of January's secession referendum.

Source: Agencies