By Anastasia Moloney

BOGOTA (Thomson Reuters Foundation) - Three environmental activists were killed per week last year, murdered defending land rights and the environment from mining, dam projects and logging, a campaign group said on Monday.

In 16 countries surveyed in a report by Global Witness, 185 activists were killed, making 2015 the deadliest year for environment and land campaigners since 2002.

"The environment is emerging as a new battleground for human

rights," the report said.

The reported killings rose nearly 60 percent from 2014. Brazil fared worst with 50 activists murdered, followed by the Philippines with 33 deaths, and 26 in Colombia, the report said.

"A major reason behind the big jump in killings is impunity, people know they can get away with these crimes," Billy Kyte, campaigner at Global Witness, told the Thomson Reuters Foundation.

"Increasingly, communities that take a stand are finding themselves in the firing line of companies' private security, state forces and a thriving market for contract killers," Kyte said.

"For every killing we document, many others go unreported."

The Inter-American Commission on Human Rights (IACHR) has also raised the alarm about growing violence and intimidation against land and environmental activists in rural Brazil.

In April, the IACHR, the body that monitors human rights across the Americas said at least six land activists were killed in Brazil during the first two months of this year.

Brazil's environment ministry did not respond to requests for comment on the rise of killings against environmentalists.

According to Global Witness, conflicts over mining projects led to more deaths of activists than any other sector.

Large-scale agricultural plantations, cattle ranching, hydroelectric dams, and logging were also to blame for the growing violence against campaigners, the report said.

Worst hit by violence were indigenous people, accounting for 40 percent of the activists killed in 2015, the report found.

Indigenous groups campaigning to protect their lands and livelihoods in Brazil's Amazon rainforest from illegal loggers were particularly hard hit, as were the Lumad indigenous tribe in the Philippines in the Mindanao region, rich in coal, nickel and gold, protesting against mining projects, the report said.

The failure by governments and companies to recognize the rights of indigenous people to decide about happens on their lands is a key driver of violence, the report said.

"Indigenous people come into conflict with companies, often with state backing, looking to develop their ancestral land without their consent," the report said.

The murder of Berta Caceres, a prominent Honduran environmental campaigner shot by gunmen in her home in March, drew international condemnation and brought attention to abuses of indigenous people.

(Reporting by Anastasia Moloney, Additional reporting from Chris Arsenault in Rio de Janeiro editing by Billy Perrigo.; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, corruption and climate change. Visit