By Chris Arsenault

RIO DE JANEIRO (Thomson Reuters Foundation) - More than 20 land rights activists have been killed in Brazil so far this year, with most deaths linked to conflicts over logging and agribusiness, data on Thursday showed, reinforcing the country's reputation for being dangerous for environmentalists.

According to data from local watchdog, the Pastoral Land Commision (CPT), 23 activists have been killed in 2016 for trying to protect forests from illegal logging and the expansion of cattle ranches and soy plantations.

Fifty land rights campaigners were killed in Brazil last year, up from 29 in 2014, according to the UK-based advocacy group Global Witness.

Released a day before the opening of the Olympic Games in Rio de Janeiro, the data indicates a crackdown on land rights campaigners in South America's biggest country with indigenous people particularly affected, activists said.

"For many visitors to the Rio Olympics, Brazil is synonymous with its vast, plentiful rainforests and traditional ways of life," said Global Witness campaigner Billy Kyte in a statement.

"Yet the people who are trying to protect those things are being killed off at an unprecedented rate."

Elizeu Lopes, a leader from the Guarani-Kaiowa indigenous group, said members of the community were being attacked by land owners and militias.

"Our people are losing our blood for plantations of sugar and soy. Our leaders are being persecuted," Lopes told the Thomson Reuters Foundation.

The Guarani-Kaiowa have been among the hardest hit communities from recent escalations in land-related violence, said Cleber Cesar Buzatto, a researcher with the Conselho Indigenista Missionario (CIMI) advocacy group.

Matto Grosso do Sul state, home to Lopes and other Guarani-Kaiowa people, has become the biggest site of clashes over land nationally, Buzatto told the Thomson Reuters Foundation.

The agricultural powerhouse on Brazil's border with Paraguay has seen at least 30 assaults on land rights activists since January, Buzatto said.

In June, dozens of armed men riding motorcycles attacked a Guarani-Kaiowa camp killing one indigenous campaigner and wounding six others, government officials said at the time.

The recent escalation of violence is linked to Brazil's broader political crisis, indigenous leaders say.

In a bid to kick-start growth in the recession-hit country, Brazil's interim government is planning to open up more indigenous areas to farming and resource extraction, Lopes and Buzatto said.

Nearly one third of territories demarcated for Brazil's indigenous people have faced invasions from illegal loggers or farmers, Buzatto said.

Brazil's National Indigenous Foundation (FUNAI), the government body responsible for safeguarding indigenous land rights, did not immediately respond to requests for comment.

(Reporting by Chris Arsenault; Editing by Katie Nguyen. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking and climate change. Visit news.trust.org)