Israel plans to arrest and deport any international peace activists who illegally enter closed military areas in the West Bank and Gaza Strip.
Israeli officials say they have been far too lenient toward foreign pro-Palestinian activists who enter the country as tourists.
The officials, speaking on condition of anonymity, say they will no longer tolerate such activists working inside Palestinian areas of the West Bank and Gaza Strip that have been placed under military rule.
Any foreigners found inside such areas will be arrested, detained and then deported. And any who are deported will be barred from entering Israel again.
The decision comes amid British press reports that the two British citizens accused of bombing a Tel Aviv café on Wednesday came to Israel claiming to be peace activists. One of the men detonated his bomb and died, along with three Israelis. The other man is at large, after his bomb apparently failed to explode.
Israeli officials say they do not expect pro-Palestinian activists to openly declare their intentions, when they arrive on international flights or at border crossings. But those activists that are identified will be sent back.
The policy is particularly aimed at volunteers for the pro-Palestinian group, International Solidarity Movement.
The activists often demonstrate against Israeli army actions inside Palestinian areas. Two months ago, an Israeli army bulldozer crushed to death an American member of the organization, Rachel Corrie, as she tried to block the demolition of a home in Gaza.
In the first sign of the crackdown, Israeli troops detained a member of the group in the southern Gaza refugee camp of Rafah on Thursday.
Israeli army officials say the woman was suspected of concealing one of the tunnels used to smuggle weapons from nearby Egypt.
Israeli officials say there has been at least one case recently of such activists helping to conceal wanted Palestinian fugitives.
In that incident, two foreigners were found hiding in the West Bank town of Jenin, with a member of the armed wing of the Islamic Jihad, an organization that carries out suicide bombings and other terrorist attacks against Israelis.