A London-based advocacy group says it has documented the killings of 185 environmental activists in 16 countries last year, nearly 60 percent more than in 2014.

Global Witness says in a report released Monday that Brazil tops the list with 50 environmental defenders slain in 2015. The Philippines is second with 33 killings, followed by Colombia with 26.

The report says last year's toll is the highest since Global Witness began collecting data dating back to 2002, making 2015 the "deadliest year on record." The group says 116 were slain in 2014.

It says land conflicts involving mining, agribusiness, hydroelectric dams and logging are behind most of the killings of environmental defenders — more than three a week, on average.