"A group of eight people calling themselves Pakistani Muslim preachers arrived two days ago and started holding unauthorised meetings, day and night, in the Bihororo mosque," the Daily Times quoted local official Alexis Manirakiza, as saying.
"Residents became suspicious at the presence of these foreigners in a remote area at a time when there is a terror threat from Somali rebels and they informed the police," he added.
A police officer said on the condition of anonymity that all the eight were travelling to the African nation on Pakistani passports.
"We're investigating to find out exactly who they are and what they were doing in this part of the world without informing the security services or the administrative authorities," the officer said.
The arrests came less than a week after the US Embassy in Burundi warned its citizens in the central African country that terror organisations, including Somalia's al Qaeda-inspired Shebab, could carry out terror attacks in February.
Security measures have been stepped up in Burundi since last week, with soldiers and police patrolling the streets of the capital. (ANI)