JERUSALEM (AP) _ Israeli police and the Shin Bet security service routinely use violence while interrogating Palestinian minors, an Israeli human rights group said in a report released Monday.

The Israeli Information Center for Human Rights in the Occupied Territories, known as Betselem, also cited other abuses, such as overcrowded cells, a lack of proper medical attention and delays in investigating complaints of police brutality.

Police said in response that they were investigating every complaint of brutality. A spokeswoman also acknowledged that prison conditions need to be improved.

''Police treat complaints of brutality by officers with special seriousness ... An investigation has been launched into every complaint submitted to police,'' said Elinoar Mazoz, who deals with public complaints.

Her statement was attached to the Betselem report. National police spokesman Adi Gonen said Monday he had nothing to add.

The report focused on the treatment of Palestinians aged 12 to 18 from Israeli-annexed Arab east Jerusalem and nearby villages, who were held at police headquarters in downtown Jerusalem.

All were detained during the 30-month Palestinian uprising on suspicion of stone-throwing, torching cars and anti-Israeli violence.

Betselem said its report was not based on a representative survey, but that the findings indicated a ''widespread phenomenon that should be viewed seriously.''

The report includes affidavits from nine minors. They were not identified by name in keeping with Israeli law.

A 12-year-old said he was placed inside a bag by interrogators. ''They put the lights out and I felt it being closed above my head. Then they began to beat me with a stick,'' he said.

A 16-year-old said an interrogator ''beat me with the end of a plastic ruler on the arms, the back and all parts of the body ... Then he grabbed a metal bar and hit me on the head. I was handcuffed all the time.''

Another 16-year-old said he was pushed against a hot-water tank and suffered burns when water spilled on his right leg.

Betselem said that in most cases, the minors did not file complaints because they do not believe in Israeli justice or fear the consequences.

It also said police were not quick enough in investigating and punishing officers engaged in brutality.

Ms. Mazoz said police investigated all complaints of brutality. She cited eight cases in which an investigation has either not been completed yet, or there was no response from the prosecutors.

The report also described the interrogation methods of the Shin Bet, which deals with those over the age of 16.

Betselem said the Shin Bet used a punishment cell, measuring about 4.5-by- 4.5 feet. It described it as a ''dark, smelly and suffocating room where prisoners are often kept for days.''

Shin Bet interrogators also handcuff prisoners in distorted poses or place them in the so-called ''grave,'' a small underground cell in which prisoners can only crouch, it said.

The Shin Bet has no spokesman.

Betselem said the police headquarters, called the Russian Compound, is badly overcrowded. In March, the compound housed 81 Palestinian youths in three cells, including one with 12 beds and 39 prisoners in it, it said.

It quoted the detention center's doctor, Andre Weissman, as saying he could not offer proper medical treatment to such a large number of prisoners.

Ms. Mazoz acknowledged that the youth ward, designed for 34 beds, usually held some 60 to 80 inmates ''because of an increase in the number of prisoners'' as compared with previous years.

She said the prisoners were given medical treatment and cleaned their cells three times a day.

Betselem also said that detainees were often forced to sign confessions in Hebrew, a language most of them cannot read.