The group, B’Tselem, points to a system of permits and checkpoints that has expanded over recent months to keep most Palestinians out of the valley. It says this and other measures that are forcing residents to leave the area appear to be a step towards seizing the land for Israel.
"Israel’s permit regime in the valley, together with statements of senior officials, give the impression that the motive underlying Israel’s policy is not based on military-security needs, but is political: the de facto annexation of the Jordan Valley," said B’Tselem.
"This annexation, similar to the de facto annexation of broad tracts of land west of the [West Bank] separation barrier, constitutes a flagrant breach of the right of the Palestinian people to self-determination."
Last week, Ehud Olmert, the acting prime minister, said Israel intended to keep control of the valley – even after it pulls out of other parts of the West Bank and draws new borders – as a defensive move. "It is impossible to abandon control of the eastern border of Israel," he said.
The sparsely populated valley – home to about 53,000 Palestinians and 6,000 Israelis in 21 Jewish settlements – is among the most fertile land in the occupied territories and an important source of produce. It also used to be a main transport route linking various parts of the West Bank. But last year the army, unannounced, started restricting Palestinian access. Only those whose identity documents show they live there are permitted to remain. Several thousand workers in the settlements or in essential areas, such as teaching and healthcare, are given permits to visit during the day.
"The closing of the Jordan Valley has caused many Palestinians who live in villages bordering the valley and work in agriculture there to lose their source of livelihood," said B’Tselem.
In recent weeks, the army has also restricted the movement of Palestinian produce out of the valley – but not from the settlements – forcing some farmers into debt and threatening their ability to maintain their livelihoods.
The United Nations Office for the Coordination of Humanitarian Affairs in the occupied territories sees the result as a valley "increasingly out of bounds for Palestinians living in other parts of the West Bank".
It says: "These permit restrictions add to a movement regime within the Jordan Valley that was already very restricted. A combination of military zones, military bases, settlements and Israeli-declared conservation areas within the Jordan Valley impedes movement for Palestinians residents and permit-holders alike."
The Palestinian planning minister, Ghassan Khatib, accuses Israel of following a strategy in the Jordan Valley that it has previously applied in East Jerusalem and elsewhere to force Palestinians out and take their land.
"They use the same tactics in every area: settlement expansion, land closure and seizure, restrictions on movement, making it difficult for Palestinians to reach services so people move away, or to restrict the growth of Palestinian areas," he said.
If Israel retains control of the valley, it would leave a Palestinian state on the West Bank entirely surrounded by Israeli territory and cut off from a direct link with the rest of the Arab world. Israeli leaders have also discussed extending the vast West Bank barrier so that it runs the length of the Jordan Valley and encircles all of future Palestine.
Captain Ishai David, an Israeli army spokesman, said the military required Palestinians who wished to enter the Jordan Valley, and who were not registered as living there, to obtain the same permit as required to enter Israel.
"This is solely a security requirement. We don’t make our operational decisions based on politics. They are made on operational needs," he said.