Palestinians detained by Israeli security forces are routinely tortured and ill-treated, according to a new report published by Israeli human rights groups yesterday. The ill-treatment, which includes beatings, sensory deprivation, back-bending, back-stretching and other forms of physical abuse, contravenes international law and Israeli law, the report says.

The Centre for the Defence of the Individual and B'Tselem, an Israeli human rights group, compiled the report after interviewing 73 Palestinians who had been arrested in 2005 and 2006.

The report found that almost 50% of detainees who were arrested in raids or at random were beaten by the army or police before they were handed over to the Shin Bet security agency for interrogation. The prisoners were interrogated for an average of 35 days and spent most of their time in tiny cells in solitary confinement. They were interrogated from five to 10 hours a day. More than half did not see a lawyer or representative of the Red Cross for the whole period of interrogation.

The report found that prisoners were effectively starved by being offered food designed to appear rotten or unappetising. Their only exercise was the walk from the cell to the interrogation room during which they were shackled, handcuffed and blindfolded. In some cases more extreme treatment was used. One in five detainees were deprived of sleep for up to three days and a quarter were beaten by their interrogators.

Out of more than 500 complaints against Shin Bet since 2001, not a single one has been upheld. Israel's justice ministry said Shin Bet interrogations were carried out in accordance with the law, although it declined to comment on the "interrogation techniques" detailed in the report.

In 1999, the supreme court banned the torture of suspects but left several loopholes which allowed it to continue.