The chief of United Nations’ human rights body expressed “deep concern” over a police crackdown on demonstrators in West Papua that has reportedly left several people dead.

Human Rights chief Navi Pillay on Thursday lamented what he described as “unfortunate examples of the ongoing suppression of freedom of expression and excessive use of force” against protesters in the Indonesian province, reports AFP.

“It is disappointing to see more people arrested for peacefully expressing their views and I call upon the government to release all prisoners in custody for crimes that relate to their freedom of expression,” Pillay said in a statement, stressing that the “peaceful exercise of freedom of expression” was not a crime.

The remarks follow media reports that revealed police shot to death two protesters in the city of Sorong during preparations for the 50th anniversary of Papua becoming part of Indonesia. At least 20 demonstrators were reportedly arrested in the cities of Biak and Timika on May 1.

Human rights violations have been rampant in Papua, which comprises most of the western half of the New Guinea island and nearby islands, including killings, torture and detention of political prisoners.

Pillay also urged Indonesia to allow international journalists and UN observers into the province, reports AFP. “While many incidents relate to communal violence, serious allegations of human rights abuses by law enforcement officials persist,” she said in a statement.