A rebel leader accused of orchestrating deadly attacks in Rwanda's border regions pleaded guilty on Thursday to terrorism and other charges, and admitted to working with foreign governments against Kigali.

The admission of conspiracy by Callixte Nsabimana, the spokesperson for the National Liberation Front (FLN), risks further escalating tensions between Rwanda's President Paul Kagame and his immediate neighbours, whom he has accused of spying.

Nsabimana was arrested last month for his involvement with FLN, an insurgent movement blamed for attacks inside Rwanda from a forested area near Burundi and the Democratic Republic of Congo.

Nsabimana plead guilty to 16 charges including terrorism and murder, and offered an unconditional apology for his crimes.