The announcement came a day after the expulsion of a Northern Irish journalist and peace activist, who was initially accused by Israel of being an IRA bombmaker.
The eight activists, who were all campaigning with the ISM when they were arrested in the northern West Bank last week, were likely to be flown back to their home countries within the next 24 hours, ISM spokeswoman Huwaida Arraf said.
Two are Swedes, two Britons and the other four from Canada, Denmark, France and the United States.
The move came after a Tel Aviv court on Thursday rejected an appeal filed by the activists' lawyer.
"The judge upheld the deportation order and decided he saw no reason to overturn the interior ministry's decision," Arraf said.
At the hearing, the judge said the activists were disturbing construction of the security fence and had not stopped at an army checkpoint, actions which constituted a disturbance of the peace and a danger to both state security and to themselves, Israel public radio reported.
"The court proceedings were not even focused on why they were arrested, it focused on their affiliation with the ISM," Arraf said. "Every time the army cries 'security', nobody asks any more questions."
A pro-Palestinian campaign group which champions non-violent direct action to protect civilians in the West Bank and Gaza Strip (news - web sites), the ISM was recently blacklisted by the Israeli authorities after a string of controversial incidents involving foreigners.
Four of the activists were detained last week in Arabbuna village near Jenin where they had set up tents to protest Israel's construction of a vast security fence.
They had been camping out at the site for three days, but were arrested on charges of "entering a closed military zone", Arraf said.
A day later, four Western and two Israeli peace activists were arrested as they tried to clear three road blocks cutting off two villages just outside Nablus.
The two Israeli activists were released without charge.
Since April 2002, nearly 60 ISM activists have been deported on "security-related" offences, said Arraf, who is one of the founders of the movement.
"We confront and challenge the illegal army policies in a non-violent manner, so whatever we do in the occupied territories is going to be seen as 'a security threat' because it always involves the army."
Israel began building the security fence in June 2002 in a bid to keep out Palestinian infiltrators.
The fence has angered many Palestinians, particularly as its construction has resulted in the expropriation of large tracts of land which they fear will end up as part of Israel in a future peace settlement.
