Israel Police have begun implementing a new method of searching Palestinian vehicles through use of nausea-inducing chemicals at a Bethlehem checkpoint, international aid workers have reported.

Since December, Israeli police officers have introduced what they call a sophisticated method of tracking explosive materials.

Palestinians with Israeli license plates, usually residents of Jerusalem or foreign residents are allowed to pass through the checkpoint. Cars traveling to Jerusalem are often asked by Border Police soldiers to park their car in a side lot with eight parking spaces near the checkpoint. Once parked, the passengers are asked to roll up all windows, apart from that of the driver – and exit the vehicle. Two tubes are then connected to the vehicle – one is connected to an air pump, the other, which passes through a tiny filter, is attached to the vehicle. A policeman with a stopwatch flicks the air pump switch.

According to Palestinians, police officers who carried out the search refused to describe the procedure. An official in the Israel Police told Haaretz that it is an approved procedure, and another police source said there is no use of any chemicals, but would not expand on the new search method.

A foreign resident who works at an international organization and must pass through the checkpoint several times a week told Haaretz that the tube is left connected for approximately 10 minutes. Afterward, the filter is removed and taken to a nearby building. The worker says she was under the impression that some kind of chemical was disseminated into the vehicle, as she and another passenger began feeling nauseous and suffered from headaches several days afterwards. The worker has informed her country’s embassy.

However, a Palestinian resident of East Jerusalem, whose car also underwent the same procedure, told Haaretz that he did not feel a thing, and that the police officers added that it was “only oxygen” being pumped into the vehicle.

Israel Police officially responded to the inquiry by saying that “as the force entrusted to protect the country’s citizens and their quality of life, it must conduct arbitrary, rudimentary checks through use of sophisticated technological means, all the while alleviating the experience of those being checked.”

Approximately three months ago, the police used bomb-sniffing dogs at the checkpoint. One man who passes through the checkpoint regularly told Haaretz that the security forces have a tendency to switch methods.