Jakarta – At least five workers were injured and 35 others were being interrogated after a clash Friday between police and protesting workers in northern Sumatra, a Indonesia's human right group said Friday.

The clash in the North Sumatra capital of Medan, occurred as about 700 workers of PT Latex Indotoba Perkasa, who were on a strike, asked the company management whether they could be allowed to return to work. However, dozens of policemen who have already guarded the glove factory, pushed the workers away, said Ridwan, a lawyer at the local Legal Aid Foundation.

The workers have began the strike some days ago, demanding higher pay and other improvements. "Four workers were injured by rubbers bullets," he said. "The other one was believed to be beaten after being taken to a police station." Police officials weren't available for comment.

According to Ridwan, 35 protesters were brought a police station for interrogation and none of them was released so far. In a letter to the local police, the foundation strongly protested what the described as "inhumanly treated" of the workers.

The Friday clash was the first in the Indonesia's third largest city since May, when thousands took to the streets in protest over price hikes. At least five people were killed and dozens were injured by gunfire.