The riot took place just as the civil war was ending
Six Sudanese men have been executed for their part in a riot at a refugee camp in Khartoum in 2005.
The men were held responsible for killing 13 policemen during the riots in which five civilians also died.
The violence flared when police tried to clear the Soba Aradi camp, which housed refugees from the two-decade long north-south civil war.
Rights group Amnesty condemned the executions, saying that the men may have been tortured into confessing.
The latest executions once again put strain on the fragile peace between northern and southern politicians.
Some of the men were reportedly from Darfur, and others were from the south.
The main southern political party, the SPLM, which is a partner in the national government, said five of them were its members.
"There was no evidence... that they were responsible," SPLM official Yasir Arman told Reuters news agency.
"This was a political issue and there were many irregularities in the court proceedings."
Amnesty said there had been a "blatant failure" to ensure that the men had a fair trial.
"These tragic deaths highlight the growing number of executions taking place in Sudan, many of which are being carried out after unfair trials," said the group's Tawanda Hondora.
According to the group, Sudan put to death 60 people last year.
The 22-year war between the mainly Muslim north and the Christian and animist south claimed the lives of some 1.5 million people.
As part of the 2005 peace deal, northern and southern politicians agreed to share power until a national election scheduled for April.