Two leaders from the main rebel alliance fighting Sudan's president and 15 members of their group were sentenced to death in absentia, their lawyer said, a move that will raise the stakes in fighting in southern regions.
Malik Agar, who was governor of Sudan's remote Blue Nile state before taking up arms, and Yassir Arman, who stood against Sudanese President Omar Hassan al-Bashir in the 2010 elections, both received death sentences, lawyer Altujani Hassan told Reuters on Thursday.
"The judge Abdelmonem Youness sentenced (them) over staging a war against the state... and terrorism," Altujani Hassan said.
Agar is now the head, and Arman the secretary general, of the Sudan People's Liberation Movement - North (SPLM-N), which is particularly active in southern Blue Nile and oil-producing South Kordofan regions.
The movement is part of a rebel umbrella group, also covering strife-torn Darfur in the west, that says it is fighting to bring in democratic reforms and topple Bashir. Khartoum has branded its members terrorists.
The sentence came weeks after the African Union adjourned talks it was brokering between SPLM-N and Sudan's government, saying both sides were deadlocked.
Fighting between the two sides has displaced or severely affected more than 900,000 people, according to the United Nations.
SPLM-N includes many fighters who sided with South Sudanese rebels in decades of civil war that ended in a 2005 peace deal that paved the way, in 2011, to the secession of South Sudan.
Both Agar and Arman were senior members of South Sudan's rebel SPLM, which is now that country's ruling party.
Khartoum has accused South Sudan of backing the rebels in South Kordofan and Blue Nile - states on the border between the two countries. South Sudan's government has dismissed the accusation.