PHNOM PENH (Reuters) - Four women land rights activists were sentenced to six months in prison by a court in Cambodia on Monday for insulting and obstructing public officials during a 2011 violent land rights protest.

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Seizure of land for development is a major cause of protests in Cambodia and other countries in the region, including Laos.

Last year was the deadliest on record for land rights campaigners, with more than three people killed each week protesting agribusiness firms, loggers, mining firms and hydro-electric dams, according to London-based NGO Global Witness.

The court in the capital Phnom Penh found activists Tep Vanny, Heng Mom, Kong Chantha and Bo Chhorvy guilty following a three hour trial and sentenced them to six months in prison over a protest in November 2011 which turned violent.

Suong Sophal, a lawyer for Phnom Penh Municipality told the court that the four women joined the protest in 2011, blocked roads, insulted and hit officials at the scene. Two security guards were injured, he said

Following the verdict, the activists yelled “injustice! injustice! injustice!”

Tep Vanny has been in pretrial detention since last month over a 2013 protest outside Prime Minister Hun Sen’s house. The other three activists remain free.

All four have a month to appeal the verdict. Activists Vanny and Chantha said they would appeal.

“I did not commit the crime,” Vanny said.

Around 50 protesters gathered outside the court on Monday calling for the case to be dropped while hundreds of police deployed to keep the peace looked on.

(Refiles to change dateline from BANGKOK TO PHNOM PENH)