Rwandan President Paul Kagame has condemned the upsurge in violence in neighbouring Burundi.
"People are being killed every day, bodies are found on the streets... Leaders are spending time killing people", he said.
On Saturday, nine people were shot dead in a bar in the capital Bujumbura.
People began fleeing Bujumbura and other parts of Burundi before a government deadline on Saturday to hand in illegal firearms.
President Pierre Nkurunziza warned that those who refused to obey the order would be "dealt with as enemies of the nation".
A cycle of violence began in April with protests against Mr Nkurunziza's controversial decision to stand for a third term.
He argued that his first term as president did not count towards the constitutional two-term limit as he was chosen by lawmakers.
In July Mr Nkurunziza was duly re-elected to a third term with 70% of the vote.
About 200 people have been killed since April.
"It is sad that the African continent has a disease, to an extent that I will be blamed for meddling in another country, that I should be diplomatic about it or I deal with it politically. But that can't be, I am being frank and open," President Kagame said.
"Leaders are spending time killing people. Bodies of dead people are scattered everywhere. Refugees are wandering everywhere - women and children - and you want to call this politics? What kind of politics is this?"
Mr Kagame was speaking on Friday - but his comments were not broadcast until the following day.
Burundi's authorities have so far not publicly reacted.
However, in the past, Burundi has accused Rwanda of training rebels seeking to destabilise the country, something Rwanda denies.
Presidents Nkurunziza and Kagame were once on good terms but fell out in 2012.
On Saturday night, gunmen shot at least nine people dead in a bar in Bujumbura.
Eyewitnesses later said they saw seven bodies lying on the floor. Two others managed to flee but later died in hospital.
Burundi's security services have been carrying out house-to-house searches in neighbourhoods of Bujumbura seen as opposition strongholds,
Earlier this week, the UN condemned the "inflammatory rhetoric" by officials in Burundi.
And the Brussels-based International Crisis Group said the language was "chillingly similar" to that used in Rwanda before the genocide of 1994.
Uganda is leading regional efforts to broker peace talks and the UN Security Council is expected to discuss the violence at a meeting on Monday.