The United Nations says 729 human rights activists have been killed in Colombia in the past two decades. That's an average of nearly three a month.

A statement from the U.N. High Commissioner for Human Rights' office in Colombia says 30 activists were slain this year through September. It adds that 20 more have been the targets of attempted murder in 2015.

The statement says an "insecure and hostile environment" persists for rights workers in the Andean nation, with authorities unable to guarantee their safety.

The figures are being published as talks on ending Colombia's half century-old internal conflict enter their third year. The government saying it expects them to wrap up in early 2016.

The chief prosecutor's office responded Friday by saying investigating violence against activists is a priority.