The ICC's prosecutor said on Monday she was opening a preliminary probe into the violence that has wracked Burundi, killing at least 430 people since a political crisis erupted following last April's elections.

"At least 3,400 people have been arrested and over 230,000 Burundians forced to seek refuge in neighbouring countries," Fatou Bensouda said in a statement, adding that she had seen evidence of imprisonment, torture and rape.

At least three armed rebel groups have emerged in the central African country since a political crisis erupted a year ago, when President Pierre Nkurunziza launched his bid for a third term in office and then won a disputed election in July.

The Office of ICC Prosecutor, Fatou Bensouda, conducts independent and impartial preliminary examinations, investigations and prosecution relating to the crime of genocide, crimes against humanity and war crimes.

Burundi ratified the Rome Statute, and as such, the ICC has jurisdiction over the three alleged crimes, committed on its territory or by nationals of Burundi since 1 December 2004, the date when the Statute came into force in Burundi.

Families of victims welcome ICC examination

"This is great news. We are extremely happy that the process is initiated ," Bernard Maingain, one of the three lawyers who have already written to the ICC and the High Commissioner for Human Rights said.

"This means the prosecutor's office can start a dialogue with the local judicial authorities to collaborate with them, put investigators on the case and start collecting evidence. The office can also organise the protection of witnesses - which is a big issue," the lawyer said. "We will, of course, collaborate with the prosecutor's office."

Maingain confirmed the 60 families have been informed of the ICC prosecutor's decision to open the preliminary examination. "For those families, this is huge. It means they know they are listened to and the crimes they (may) have been victims of are taken into consideration."

Human Rights Watch also welcomed the decision.

"The announcement that the International Criminal Court prosecutor is opening a preliminary examination of the situation in Burundi should be a wake-up call that the era of impunity for grave human rights violations in Burundi is over. Allegations about crimes there and those who commit or order them will now be under the Court's scrutiny," Géraldine Mattioli-Zeltner, the international justice advocacy director at Human Rights Watch, said.

"The Burundian authorities have the legal obligation to stop the abuses that have been escalating in Burundi since 2015 and to hold those responsible to account, but have failed to do so. The ICC was created as a court of last resort, to ensure that justice is done for grave international crimes. Burundi should fully cooperate with the Court's preliminary examination."

Click here for the full statement by ICC prosecutor Fatou Bensouda