Nairobi (AFP) - Families were fleeing their homes in Burundi's capital on Sunday, over fears the government will unleash a fresh wave of bloodletting as part of a crackdown to stamp out resistance to the president.

Burundi has been engulfed in violence triggered by President Pierre Nkurunziza's successful bid to win a third term in office, with bodies found dumped in the streets on a nearly daily basis.

International alarm has grown ahead of a deadline of midnight on Saturday for civilians to hand over weapons or face a new regime crackdown, drawing warnings from the head of the UN, Washington and the world's only permanent war crimes court.

Fearing a fresh escalation of the bloodshed, people started leaving parts of Bujumbura that have seen the worst recent violence.

"I was terrified, I understood that this time they would kill every last one of us," said Marie, a secretary in her forties who took her five children to a relative's house in a calmer part of the capital.

A resident of the flashpoint Mutakura district, who asked not to be named, added: "Mostly men have stayed behind to protect their belongings... all the rest have fled."

At least 200 people have died in the latest turmoil and 200,000 have fled the country, sparking fears violence gripping the the central African country could spin into mass bloodletting and even genocide.

"Inflammatory rhetoric deployed in recent days by some government officials and President Nkurunziza's planned security crackdown this weekend are increasing the risk of an outbreak of mass violence," the US said Saturday.

But the government dismissed the concerns, saying it wanted only to crush "terrorism" and comparing the fight to Somalia's struggle against Islamist Al-Shebab insurgents that Burundi is fighting as part of an internationally backed African Union force.

"There will be no war or genocide," presidential communications chief Willy Nyamitwe told AFP on Saturday.

"It is amazing to see that a government that wants to put an end to terrorism is criticised instead of being encouraged," he added.

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- Echoes of Rwanda -

The UN Security Council is to meet on Monday to discuss the crisis.

UN Secretary General Ban Ki-moon said Friday that the discovery of bodies -- "many apparently summarily executed" -- has become a "regular occurrence" in Burundi's capital Bujumbura.

Bloodshed has risen ahead of the deadline to return weapons, and on Friday the son of a leading Burundian rights activist was found dead hours after he was arrested in the capital, his family and witnesses said.

Last week, the country's Senate president Reverien Ndikuriyo threatened to "pulverise" regime opponents who do not lay down arms before the deadline which expires later on Saturday.

"Today, the police shoot in the legs... but when the day comes that we tell them to go to 'work', do not come crying to us," he said.

The loaded term "work" was a euphemism used in Rwanda during the 1994 genocide to describe the mass killings of at least 800,000 mainly Tutsi people by extremist Hutu militias.

"The language is unambiguous to Burundians and chillingly similar to that used in Rwanda in the 1990s before the genocide," the International Crisis Group (ICG) think-tank said.

Minister of public security and regime number two Alain-Guillaume Bunyoni this week reminded inhabitants of the restive neighbourhoods -- particularly Tutsis -- that they were a minority compared to the Hutus who back Nkurunziza.

"If the police fail, there are nine million citizens to whom it would be enough to say: do something," he said.

- 'Dark days lie ahead' -

The rising unrest has sparked fears Burundi could slide back into conflict after its 1993-2006 civil war, when 300,000 people died as rebels from the majority Hutu people clashed with an army dominated by the minority Tutsis.

"Ask anyone in Bujumbura and they will tell you the same thing: dark days lie ahead," Carina Tertsakian from Human Rights Watch warned.

"Burundi seems to be descending into uncontrolled violence. A frightening lawlessness is taking hold, which some authorities appear to be taking advantage of to justify brutal repression."

In The Hague, the prosecutor of the world's only permanent war crimes court warned on Friday she would take action if wide-scale abuses were committed in Burundi.

The political crisis has seen many independent media outlets shut down and many journalists have fled the country or gone into hiding because of threats and attacks.