Israeli troops would have the power to deport people within 72 hours
Israel has imposed a military order which rights groups say could see tens of thousands of Palestinians deported from the occupied West Bank.
The order, which came into force on Tuesday morning, could have "severe ramifications" for people in the West Bank, human rights groups say.
It classifies people without the right Israeli paperwork as "infiltrators".
Israeli military sources say the move will allow more judicial oversight, and only affect a small number of cases.
The Israeli military says that existing orders already allow for the deportation of West Bank Palestinians deemed by Israel to be there illegally.
It says the new order allows for each case to be reviewed by a military judicial panel before deportations are carried out.
The wording of the order, known as the Order Regarding Prevention of Infiltration, has been amended from when it was originally drawn up in 1969.
The definition of "infiltrator" was then: "A person who entered the area knowingly and unlawfully after having been present in the east bank of the Jordan, Syria, Egypt or Lebanon following the effective date (of the order being given)."
Under the new order this is to be changed to: "Infiltrator - a person who entered the area unlawfully following the effective date, or a person who is present in the area and does not lawfully hold a permit."
"The orders are worded so broadly such as theoretically allowing the military to empty the West Bank of almost all its Palestinian inhabitants," a letter written by human rights organisation HaMoked and signed by 10 other groups to Defence Minister Ehud Barak said.
The document itself does not specify exactly what is meant by "a permit", but Israeli military sources said that anyone registered with the Palestinian population registry - which is overseen by Israel - would be considered lawfully present.
The group of 10 human rights groups in Israel who condemned the new orders included HaMoked, B'tselem, the Association for Civil Rights in Israel, and Rabbis for Human Rights.
Sarit Michaeli, Director of B'tselem said there were two groups the organisation believed were likely to be affected most.
The first are those whose identity cards show them as Gazans, but who have been living in the West Bank, and who may even have had children while living there.
Israel has not allowed many of them to change their status from Gaza to the West Bank, despite the fact that, under the Oslo Accords, Gaza and the West Bank were to be considered a single entity.
The second group are people from other countries who have married Palestinians, who entered on limited-time visas and have stayed, but not been granted official status.
Ms Michaeli said human rights groups believe there are tens of thousands of people in each category.
But a senior Israeli military official, speaking anonymously, said there were "almost no" foreign nationals living without the necessary documents in the West Bank, after most were legalised in the past few years.
The official also said only five people with Gaza identity cards had been sent back to Gaza from the West Bank so far in 2010 and the numbers involved were not large.
Under the military order, deportations from the West Bank can be carried out within 72 hours.
Suspected "infiltrators" could also be jailed for up to seven years under the new orders.
Anyone being removed might also have to pay for the cost of their own deportation, the order says.
Correspondents say there is great uncertainty among Palestinians about what the new military order means and who it is likely to affect.
Ms Michaeli said the order would also undermine the Palestinian Authority, led by Palestinian leader Mahmoud Abbas.
"That such a sweeping order, such a draconian order, was allowed to pass without any amount of public debate or proper advertisement, an order which could effect every Palestinian, we intend to fight it in the courts," she told the BBC.
Chief Palestinian negotiator Saeb Erekat said the new measures "belong in an apartheid state".
"Extensive in scope, they make it infinitely easier for Israel to imprison and expel Palestinians from the West Bank," he said in a statement.
The IDF said in a statement that all the requisite notices of the change to the orders had been given.
"The IDF is ready to implement the order, which is not intended to apply to Israelis, but to illegal sojourners in Judea and Samaria [the West Bank]. This is a pre-existing order which was corrected to assure judicial oversight of the extradition process," a statement from the IDF said.
Close to 500,000 Jews live in more than 100 settlements built since Israel's 1967 occupation of the West Bank, including East Jerusalem. The settlements are illegal under international law, though Israel disputes this.
There are around 2.5 million Palestinians living in the West Bank.