The UN Security Council has unanimously adopted a resolution setting the stage for deployment of UN police to Burundi, where political unrest that has lasted nearly a year has killed more than 400 people and displaced tens of thousands.

The resolution, agreed upon by the 15-member council on Friday, asks Secretary-General Ban Ki-moon to present options within 15 days for deployment of UN police in order to monitor the security situation, promote respect for human rights and advance the rule of law.

Burundi has been hit by unrest since April 2015, when President Pierre Nkurunziza announced his decision to seek a third term, which he went on to win in a July election.

His government has been wary of outside intervention, last year rejecting the idea of an AU peacekeeping force and calling foreign troops an "invasion".

The French-drafted resolution welcomed the consent of Burundi's authorities to increase the number of African Union human rights observers from 100 to 200 and allow 100 AU military experts. It notes that 30 human rights observers and 15 military observers have been deployed so far.

The final draft was changed to overcome an objection from the United States.

A reference to "disarmament" was removed from a section calling for the UN team to work with the government and other parties "in the areas of disarmament, security and rule of law".

The US had been concerned about linking the UN efforts to broker peace in Burundi with the country's security forces, who have been accused of human rights abuses, one council diplomat told the Reuters news agency.

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The resolution strongly condemns human rights violations including extrajudicial killings, sexual violence, torture, intimidation of civil society organisations and journalists and restrictions on fundamental freedoms.

More than 250,000 people have been forced to flee to neighbouring countries owing to a climate of fear.

Burundi's UN Ambassador Albert Shingiro was quoted by the the AP news agency as saying that the government "is ready to discuss and to come to an agreement on the nature, the size and the missions" of a UN police presence that is unarmed.

He noted that the option of an "international unarmed presence" was a recommendation of the last AU heads of state summit.

Two weeks ago, UN human rights chief Zeid Ra'ad Al Hussein told the council that many people in Burundi are living in "terror", with almost daily grenade attacks and arbitrary arrests, while the perpetrators go unpunished.

The resolution reiterates deep concern at "the persisting political impasse in the country" and stresses the urgency of convening "a genuine and inclusive inter-Burundian dialogue."