The army said on Tuesday eight members of Hamas and five followers of Islamic Jihad would be initially transferred to an Israeli detention centre in Gaza and would then be released. They were given 48 hours to appeal the move.
The activists, who all hail from the West Bank, will not be allowed to leave Gaza for the next two years.
"This measure has been taken in order to reduce the number of anti-Israeli attacks which have recently taken place," a military source added.
Administrative detainees are prisoners kept in custody who have not been convicted of any offence.
"These expulsion measures are being taken against Palestinians who cannot be brought to justice without revealing sources of intelligence which led to their arrest," said one source.
Palestinian President Yasir Arafat warned that Israeli deport plans marked the start of a wider policy of transferring Palestinians from their homes.
"Transfer starts with these deportations," said the veteran leader. "It is part of a conspiracy against the Palestinian people."
A policy long championed by many in Israel's radical right,
"transfer" would see the estimated 1.5 million Palestinians in the West Bank and Gaza Strip moved to neighbouring Arab states.
If carried through, it will be the largest number of
Palestinians to be expelled from the West Bank since May 2002, when 26 activists were transferred to Gaza at the end of a siege at the Church of the Nativity in Bethlehem.
"Transfer starts with these deportations"
Yasir Arafat, Palestinian President
Those affected would have two days to launch an initial appeal before a military judge and could appeal to the Supreme Court if rejected.
Palestinian prime minister, Ahmad Quraya, blasted the decision, saying it demonstrated Israel's determination to undermine the peace process.
"Israel is committing flagrant acts of aggression to sabotage
peace efforts," he said.
Chief Palestinian peace negotiator, Saib Uraikat, also denounced the decision as "a flagrant violation of the Fourth Geneva Convention".
But an Israeli source claimed the principle of expulsions had been approved by the Supreme Court last September.