Colombia's civil conflict is posing a growing threat to the survival of some of the world's oldest and smallest indigenous groups, the UN has warned.
Colombia's indigenous communities total about one million people
More than 1,700 people fled after two of their leaders were killed last week.
"All indigenous communities have close links to their ancestral land, on which their cultural survival depends," UNHCR spokesman William Spindler said.
Colombia's indigenous groups are often caught up in the conflict between government forces and left-wing rebels.
People from the Wounaan indigenous group fled their homes in the north-west region of Choco last week after two of their leaders were murdered in the space of 24 hours.
"There are fears that more assassinations could follow as other leaders have received threats," Mr Spindler said.
Displaced Wounaan who have arrived through the jungle to the town of Istmina said people were afraid of coming under attack.
The director of the UNHCR's bureau for the Americas is going to Istmina on Wednesday to meet the displaced and local authorities.
The UNHCR has also expressed grave concern about the fate of the Nukak indigenous people, a small group of nomadic hunters whose existence was unknown to the outside world until 1988.
Indigenous groups are at risk of violence and forced displacement
Last week, 77 Nukaks arrived in the town of San Jose del Guaviare in the south-eastern department of Guaviare.
They had been walking for four months after being forced to leave their ancestral territory, Mr Spindler said. They were in poor health and malnourished, and are getting emergency help from the Colombian authorities.
This is the third displacement since 2003 and means about half the total Nukak population, estimated at around 500 people, have been forced to abandon their land.
Colombia's indigenous communities total about one million people out of a population of over 45 million.