Jerusalem  - Israeli human rights group called on the Israeli government Wednesday to ditch a practice, under which it jails without trial Palestinians it deems a "security threat" for extendable periods of up to six months.

Some 335 Palestinians are currently held by Israel without trial in administrative detention, including three women and one minor, said the rights groups.

The practice, known as "administrative detention," is used by Israeli authorities against Palestinians who they say are involved in militant activity and therefore pose a "real and imminent" threat.

An anticipatory measure, Israel says it is a "last resort" to put militants, who cannot stand trial for past acts they have already carried out, behind bars and avoid future attacks they and the armed groups they belong to are planning.

But B'Tselem and Hamoked, in a 44-page report entitled Without Trial, charged that Israel's extensive use of administrative detention breaches international law, which permits it "only in very extreme cases."

The vast majority of those held in administrative detention are freed after up to two years at the most. But 28 Palestinians have been held for longer - between two to four years - and many also testify they go through a cycle of arrests and re-arrests.

The detention orders need to be extended by a judge after six months, but the B'Tselem-HaMoked report charges this only gives a "semblance of a fair judicial process," because the judges often rely on classified intelligence reports, which makes it all but impossible for the detainees' attorneys to refute the allegations made against their clients, or offer counter evidence.

As a result, most detention orders are approved by the Israeli military courts that review them, the report said.

It detailed nine cases, including one of two female Palestinian cousins, who were 16 when taken from their West Bank village homes by Israeli soldiers for their alleged involvement in planning armed attacks against Israel, and brought to women's jails in Israel, where they had to share their wing with adult convicted female criminals. They were released eight months later without having been tried.

"HaMoked and B'Tselem call on the government of Israel to release the administrative detainees or to prosecute them according to the standards of international law regarding due process," the two groups said in a statement sent to journalists.

The Justice Ministry said in a response that Israel was engaged in an "armed conflict" with Palestinian militant groups, but was taking "many measures to reduce, to the extent possible, the use of administrative detention."

It pointed at a "steady decline" since the height of the Palestinian uprising in the early 2000s, when the number of administrative detainees stood at around 1,000. (dpa)