Israel has stopped issuing work permits to foreign aid workers in the West Bank and East Jerusalem, sparking fears about the future of relief operations in the Palestinian territories.

The Israeli Interior Ministry has issued only tourist visas to aid groups such as Oxfam, Médecins sans Frontières and Save the Children since before Christmas. They say that their legal situation is now precarious and that some staff have been denied entry by Israeli border officials who also control all entry to the West Bank.

The move came amid pressure from right-wing Israeli groups to crack down on non-governmental organisations, which are often seen as having a political, anti-Israeli bias.

Early last year an Israeli group, NGO monitor, forced the New York-based Human Rights Watch to suspend a weapons specialist who had written a scathing report on Israel’s use of white phosphorus during its Gaza offensive. The group tracked down anonymous comments that the researcher had made on online discussions for collectors of Nazi memorabilia.

Some left-wing Israeli groups have accused Israel of “declaring war” on foreign groups such as Human Rights Watch and Oxfam, which have been critical of Israel’s blockade of Gaza.

Aid groups are now worried that the decision by the Interior Ministry could inhibit their work to provide medical support, welfare and basic supplies to hundreds of thousands of Palestinians.

“We are now in a very precarious legal position,” said Jean-Luc Lambert, head of Médecins sans Frontières in Jerusalem: “We can’t get B1 (working) visas, only B2 (tourist) visas, and with this it is not permitted for us to work.”

Mr Lambert said that aid groups had been given verbal reassurances from the Israeli authorities that they would be able to continue their operations in the 60 per cent of the West Bank under Israeli control, in Arab East Jerusalem and in Gaza — whose only open crossings are on its frontier with Israel, controlled by Israeli forces.

During the Israeli offensive against Gaza, however, the authorities prevented many aid groups from entering the area, raising concerns about the value of any verbal agreement. “This leaves NGOs vulnerable to border guards’ interpretation of the rules,” said Mr Lambert, making the development a serious source of concern for 150 international organisations.

He said that technically, under the new rules, he could not work in his East Jerusalem headquarters, nor hold a meeting in the predominantly Arab half of the city that Israel captured in the 1967 Six-Day War and which both sides claim as their capital.

“Officially, East Jerusalem belongs to the West Bank, but for Israelis it belongs to Israel.”

Another Western aid worker said there was a fear in the aid community that the move was a first step towards expelling them from East Jerusalem, where Binyamin Netanyahu, the Israeli Prime Minister, has said that Jewish settlement building will continue despite protests from the United States and the European Union. “There’s a feeling that we are going to be pushed out of East Jerusalem,” he said.

The Interior Ministry denied that visas had been stopped and said that, if aid organisation workers spent most of their time in the West Bank, they would need to apply to the Palestinian Authority or the Israeli Army for permits.

Aid workers said that they usually worked in both Israel and the West Bank, with their logistical hubs in the former, with its access to international sea, land and air routes, while bringing relief to Palestinians in the isolated West Bank and the Gaza Strip. The Interior Ministry said that it was holding discussions with the army about how to deal with such cases.

NGOs operating in Gaza also worry that a lack of work permits could mean that they would not be able to enter the sealed-off coastal enclave through Israel, and may have to take in supplies through Egypt.

Catherine Weibel, of Oxfam, said that the issue of Israeli work permits was generating much anguish among foreign aid workers, many of whom worry that they could be denied permission to re-enter.