Israeli bulldozers arrived at the rust-coloured fields of Ras al-Ahmar early in the morning on the day when Barack Obama, a few hundred miles to the south in Cairo, gave his closely watched speech to the Muslim world.

Within minutes, the bulldozers had demolished 15 shacks – the homes of Palestinian farmers and their families – as well as 30 animal pens and 18 traditional ovens, implementing eviction orders given by the Israeli military a week earlier.

The UN said 128 Palestinians, including 66 children and 34 women, were displaced from this agricultural land, deep inside the occupied West Bank and barely a few miles from the border with Jordan.

Eviction orders still hang over dozens more farmers in the area, all of whom live close to three Israeli agricultural settlements which are among many built along the fertile Jordan valley.

The demolitions drew little international attention: they happen often and these farmers are remote and poor, at the bottom of the Palestinian social scale.

But a new report by three aid agencies, including Save the Children UK, released today, highlights the growing rate of demolitions and the often devastating effect they have on the families left homeless.

Since Israel captured and occupied the West Bank, east Jerusalem and Gaza in 1967, more than 24,000 Palestinian homes have been destroyed.

Israel says demolitions like those in the Jordan valley are carried out in accordance with its laws and that Ras al-Ahmar, in particular, is in a closed military zone used for weapons training.

Indeed, there are signs at the entrances to some nearby roads reading: "Danger. Firing Area. Entrance forbidden".

Ras al-Ahmar is also on land designated as Area C, which gives Israel full administrative and security control under the Oslo peace accords of the mid-1990s.

But the demolitions and evictions are on land in the shadow of Israel's settlements, which are illegal under international law.

Critics say the demolitions breach the Geneva conventions, which forbid the destruction of private property except when absolutely necessary for military operations.

Despite saying for the first time yesterday he would accept an independent Palestinian state, the Israeli prime minister, Binyamin Netanyahu, has praised the Jewish settlers who live in east Jerusalem and on the occupied West Bank and refused US calls for a halt to all settlement growth.

The farmers themselves see the challenge they face as a struggle for survival. Lufi Jabbar, 48, and his seven children watched the Israeli bulldozers demolish his shack and animal pen at Ras al-Ahmar.

A few hours later, he simply rebuilt the wood and canvas home a stone's throw away. "What am I going to do? Whenever they demolish I will rebuild," he said.

He was born in Ras al-Ahmar, where his father was also a farmer, grazing sheep and goats. "This is the only life I know," he said.

Like others, Jabbar insists he has documents proving ownership of the surrounding grazing land. "Without the grazing area, I'm done with life," he said. "But they want to clean the Palestinians from here and they want to expand the settlement."

On the hilltop behind him is the Jewish settlement of Beqa'ot, built in 1972 and home to about 150 settlers.

Its fields are well watered and bright green, in stark contrast to the dry and dusty Ras al-Ahmar and the rest of the valley. In the next valley is the settlement of Roi, built in 1976 and home to about 120 settlers.

Many of the Palestinians have been evicted several times. Abdullah Bisharat, a 62-year-old father of 18, was born in al-Hadidiya, a nearby hamlet now in the shadow of Roi.

His home there was first demolished in 1983, and three more times up to 1997. Two years ago, he lost an appeal to the supreme court and moved from al-Hadidiya to land owned by his family in Ras al-Ahmar. His home there was demolished a year later.

"The Israelis have used many mechanisms to make our lives impossible," he said. "But I won't leave my land because, if I do, they will confiscate it. We are here to protect the land."

The Save the Children report, based on interviews with evicted families, found that an average of three houses are being demolished every day, with some villages given blanket demolition orders.

More than 300,000 Palestinians risked losing their homes, it said.

Children from homes that were demolished showed a clear decline in mental health, with classic signs of trauma: withdrawal, depression and anxiety.

Most families spent up to two years looking for a new permanent home and a quarter of families left homeless were forced to divide themselves to find somewhere to live, the report said.

"Families lose everything when their homes are demolished – clothes, food and furniture are all buried in the rubble," Salam Kanaan, the country director for Save the Children, said.

"There is precious little help for these families who are left with nothing – no support, no protection."

The report called on Israel to halt house demolitions and on the Palestinian Authority to advocate against demolitions and provide help for those left homeless, particularly children.