Ninja-style killers have gone on a murder spree in the past few months in East Java, targeting Muslim clerics and practitioners of black magic, police and local residents said Thursday.

A number of the victims around the port town of Banyuwangi appear to have been killed for practicing black magic, they said."For the past three months, according to our investigations, the total number of the victims is 86," provincial police chief Major-General Muhammad Dayat told reporters.

He said police had detained dozens of suspects but declined to say who they were or whether anyone had been charged.

"Based on information that we have gathered from the suspects, the killings were motivated by revenge and money, but the killers said their actions were carried out for the good of the people."

More than 100 people protested in Banyuwangi on Thursday, demanding security forces catch the killers, who some locals said were clad in black Ninja-style uniforms.

"Nowadays the killings are no longer of people suspected of practising black magic. In the past one month, most of the victims were Moslem clerics," Banyuwangi police chief Edi Murdiyanto said.

Banyuwangi's chief of military police, Subirahardjo, told Reuters a curfew had been imposed in the town since Tuesday due to rising tension as a result of the killings.

The town's port, a major departure point for the holiday island of Bali, had also been temporarily closed, police said.

"The situation is very tense now," one local resident told Reuters by telephone.

Indonesia has faced mounting crime, looting and unrest in recent weeks as the country's economic crisis deepens and prices of basic commodities spiral upward.