The International Criminal Court said on Thursday it would extend the remit of its investigation into suspected war crimes in Ivory Coast to cover the country's first civil war which began in 2002.
The Hague-based war crimes court had already opened an investigation into crimes allegedly committed by forces loyal to Ivory Coast's former president, Laurent Gbagbo, as well as those backing his rival, President Alassane Ouattara, during a second civil war that followed disputed elections in November 2010.
Gbagbo was captured and flown to The Hague in December 2011 to appear before the court and is expected to face charges of crimes against humanity.
On Thursday the court announced it would extend the remit of its investigation as far back as September 19, 2002, when the country's bloody first civil war broke out. Ivory Coast has previously accepted the court has jurisdiction from that date.
The court justified its decision by saying that the violence which occurred during the period was part of a prolonged power struggle that culminated in the disputed 2010 election.
"There is reasonable basis to believe that, in the course of these events, acts of murder and rape that could amount to war crimes or crimes against humanity were committed," it said in a statement.
The 2010 election was meant to draw a line under the country's first civil war, which had split Ivory Coast into a government-held south and rebel-held north.
But Gbagbo's refusal to accept defeat, despite UN-certified results showing he had lost, reawakened old ethnic tensions.
About 3,000 people were killed and more than a million displaced in a second four-month civil war after Gbagbo refused to cede power to Ouattara.
The ICC has charged Gbagbo with individual criminal responsibility on four counts of crimes against humanity: murder, rape and other forms of sexual violence, persecution, and other acts.
The ICC prosecutor, Luis Moreno-Ocampo, has said he is likely to be joined in the dock by other high-level suspects from both sides of the conflict.