Burundi's President Pierre Nkurunziza has said his country faces a specific threat from the Somali Islamist movement al-Shabab.
He was appearing in public in the capital Bujumbura for the first time since a failed coup bid against him was launched on Wednesday.
Mr Nkurunziza made no mention of the coup attempt, which came after weeks of sometimes violent protests against him.
A spokesman for al-Shabab called his remarks "dumbfounding".
Sheikh Ali Mahamud Rage said Burundi's problems were "clearly domestic".
"We think that this is an attempt by him to appease his people, who are standing in the streets protesting against his dictatorship, or to divert the world's attention from him while he possibly prepares his mass revenge," the spokesman told Reuters news agency.
On Saturday 18 people appeared in court on charges of helping the attempted coup.
The alleged ringleader, Godefroid Niyombare, is still on the run.
Activists say they are planning more protests for Monday against Mr Nkurunziza's decision to seek a third term in office in elections due next month.
The BBC's Karen Allen, who is in Bujumbura, says the president's claims have been met with scepticism from many, who fear they could provide a pretext for the security services to crack down hard on Monday's demonstrations.
On Saturday, our correspondent saw evidence of a retaliatory attack at a hospital where soldiers involved in the coup were being treated. Three soldiers were taken from the building and bundled into a police van.
Mr Nkurunziza was out of the country when military officers launched their coup bid against him on Wednesday. He returned on Friday after forces loyal to him had regained full control.
The president said he came to his office to speak on the telephone with the leaders of Kenya and Uganda regarding a specific threat from the Islamist group al-Shabab.
Al-Shabab, which is battling the UN-backed government in Somalia, has carried out a string of attacks in neighbouring Kenya and is allied to al-Qaeda.
Burundi has troops fighting al-Shabab, as part of the African Union mission in Somalia.
The US has advised its citizens to leave the country because of the deteriorating political situation, and had previously warned about the threat from al-Shabab.