A statement from the office of Tanzanian President John Magufuli said the court's decision 'compromised efforts' of an East African Community (EAC) committee 'charged with seeking a resolution to the Burundi conflict.'
The committee is led by Uganda President Yoweri Museveni and former Tanzanian President Benjamin Mkapa.
Museveni on Saturday accused the ICC of 'interfering in the efforts of the EAC.' He currenty heads the EAC, a regional bloc made up of Tanzania, Uganda, Kenya, Rwanda, Burundi and South Sudan.
On Friday, Burundi's government said it would not cooperate with the proposed ICC investigation. The east African nation recently withdrew from the ICC charter, but the court argues the pullout does not affect its jurisdiction over crimes committed earlier.
Speaking to reporters in Burundi's capital, Bujumbura, Justice Minister Aimee Laurentine said the ICC has no right to conduct an investigation in her country.
'Burundi, not being a state party to the ICC statute, is not concerned with those so-called decisions of that court,' said Laurentine . 'The government of Burundi rejects that decision and reiterates its firm determination that it will not cooperate with the International Criminal Court or any other fraudulent manipulation intending to facilitate extended mandate of the ICC in the territory of Burundi.'
The government response came a day after three judges at the ICC authorized the prosecutor to open an investigation into alleged human rights abuses committed inside and outside Burundi between April 2015 and October 2017.
Burundi became a member of the Rome Statute, the treaty that established the ICC, in 2004. The country announced the plan to withdraw from the statute in October 2016 and the notification took effect last month. Burundi accused the court of targeting African countries.
'No crime can go unpunished'
Vital Nshimirimana, who heads Burundi's Forum for Strengthening the Civil Society, said pulling out of the ICC wouldn't save those behind crimes against civilians.
'Now it's very well-informed that it cannot escape justice because victims are crying for justice and today no crime can go unpunished in the modern world,' said Nshimirimana.
According to human rights organizations, between April 2015 and May 2017 at least 1,200 people were killed, 900 disappeared forcefully and more than 10,000 people were illegally detained amid Burundi's political unrest.
Security forces and the ruling party youth wing better known as Imbonerakure have been accused of being behind much of the killings of civilians and political opponents.
Laurentine said her country has the capacity to prosecute those behind the human rights violations.
'Burundi has efficient and able institutions and legal mechanisms to conduct investigations and to take it before justice of any kind of crimes committed in its territory without discrimination, fear or favor,' she said.
Some rights groups, however, doubt that Burundi's judiciary can give justice to the victims of political violence.