Dominic Dim Deng, the Defense Minister of South Sudan, perished along with 23 other people that were unlucky enough to be aboard the plane that crashed near the southern town of Rumbek, authorities said.

The Defense Minister was on his way to the regional capital Juba accompanied by a military delegation. They were returning from the city of Wau where they had attended a political conference.

The 23 victims - 21 passengers and two crew members - included presidential adviser Justin Yak. His wife was also on that flight.

The current state of the investigation leads to the conclusion that the cause of the crash was an engine trouble developed by the aircraft during the flight. Authorities ruled out a possible attack.

"Twenty one passengers were killed and either two or three crew members. Two engines failed and there was nothing the pilot could do," said First Vice President southerner Salva Kiir during a news conference.

The site of the crash was cordoned off so the investigators could do their job, said South Sudan Information Minister Gabriel Changson Chang. A helicopter was also sent to the crash site.

The plane was a Beechcraft 1900 operated by South Sudan Air Connection. It was flying from Wau to Juba, the United Nations informed.

The jet crashed about 375km (220 miles) west of Juba, said South Sudanese Deputy Prime Minister Riek Mashar according to French news agency AFP.

Dominic Dim, a major general in the army, took office last July in a cabinet reshuffle.