At least six indigenous people were killed and another 10 are missing in northeast Nicaragua following a "massacre" of a protected community by armed outsiders, rights groups said on Thursday.

The attack took place in the Bosawas Biosphere Reserve, a hilly tropical forest area, against the Mayangna community, the Inter-American Commission on Human Rights (IACHR) said on its Twitter account.

Neither the police nor government have commented on the attack.

Bosawas is a protected UNESCO biosphere reserve that is rich in gold and timber, and inhabited by two groups of indigenous people.

However, the area has come under threat from what rights groups describe as "colonizers" trying to appropriate indigenous land to exploit the rich natural resources.

The Fundacion del Rio environmental organization said 80 armed colonizers attacked the community at a place called Alal and torched their homes on Wednesday night with the intention of stealing their land.

"It was a massacre," the organization's representative Amaru Ruiz told AFP.

"The indigenous people are faced with invasions of this type and massacres that put these communities' lives at risk."

"This attack is another example of the state's indifference to the sufferings of the communities of indigenous Nicaraguans faced with illegal attempts to occupy their land," said Erika Guevara-Rosas, Amnesty International's Americas director, on Twitter.

IACHR said these types of attacks have been going on for years and reminded the government of its obligation to protect indigenous communities.

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