The report, Unpaid Debt, argued Sudanese were forced to flee or were killed during this time as Sudanese soldiers in cooperation with militant groups attacked civilians to drive them away from the field where several oil companies extracted oil.
The report is based both on eyewitness accounts, aerial photographs and satellite images.
Swedish foreign minister Carl Bilt has served on the board of Lundin between 2001 and 2006. Lundin Oil told Swedish Television that they are ready to cooperate with the investigation.
The prosecutor Magnus Elving told news agency TT that there is reason to believe that crimes have been committed and that there may be a Swedish connection with those crimes. Elving also said that this type of investigation is very extensive and usually takes a long time.
Thomas Bodstroem, the chairman of the justice committee in Swedish parliament and a Social Democrat, wrote on his blog Monday and called for Bildt to take a "time-out" from politics. Meanwhile, the Swedish Left Party is calling for Bildt's resignation. Bildt has dismissed those calls.