Looking for children's activities in Gulf War-obsessed Jerusalem, a group of parents recently took our kids to the zoo.

The West Bank town of Qalqilya hosts a small one. The children were excited: "Look, there's the zoo!" they said, as we approached. "There's the wall all round it. That must be to keep the lions in".

Sure enough, there was a massive concrete wall snaking its way along the new Israeli highway. 24 feet high, it would cage in King Kong. The children began a debate: what animal could get over the wall: a giant kangaroo, a blue whale?

The red roofs of illegal Israeli settlements crowned the hills around us. Suddenly (there had been no signposts to Qalqilya, as though the map lied), sheltering in their lee, was an old town with minarets and market gardens.

The wall we had seen was not to keep the animals confined. Even the children realized this as we drove up to the check-point that is now the only way in or out of the town. Forty-five thousand people live inside, entrapped by an impregnable barrier, with Israel Defence Forces (IDF) soldiers deciding whether or not they may pass.

Qalqilya lies almost on the pre-1967 border, and the wall we had seen follows the Green Line at this point. In most places, however, the 'security fence' is being built well inside the West Bank, and thereby divides communities from their lands and from one another. Not only is the 'security fence' a massive land grab constituting 10% of the West Bank, it also traps 95,000 Palestinians on the 'wrong side'. Sandwiched between Israel and the wall, unable to reach their own services, not permitted access to those in Israel, these Palestinians will have little choice but to perform 'voluntary transfer'.

We were allowed through the check-point because our vehicles had diplomatic license plates and because we were not Palestinian, though it took a while for the soldier, a young immigrant from the Ukraine, to ponder our passports and say "OK". Palestinians must apply to the IDF for a permit even to step outside their town, and any incoming or outgoing goods must first be unloaded at the check-point, then loaded up again onto another truck on the other side.

We went to see the wall close up, from the inside. Where there had once been nurseries growing a host of different shrubs, fruits and vegetables, there was now a barren no-man's land. It is difficult to appreciate the true scale of the wall until you walk right up to it. It was while we did this that the IDF shot at us, a group of parents and children, twice, to force us back.

As though the feeling of oppressive incarceration were not already enough, to complete the visual imagery there were watchtowers along the length of the wall: rounded, lowering keeps, capped with low-domed concrete roofs with narrow slits for soldiers to peer out and take pot-shots at the town's inmates.

We left the wall and went to the zoo. An ordinary, well-kept little zoo whose space for animals was far too limited. It is out of the ordinary because it is a zoo within a zoo. The inner perimeter – the animal zoo – encloses bears, a giraffe, a lion, crocodiles, birds and monkeys. The lion obligingly roared, the hippo came to the fence and yawned open her mouth to show us her vast, fleshy palate, and the giraffe stretched his head over the fence to be fed by the children.

Qalqilya itself did not start life as a zoo whose population, like the giraffe, must be fed from across a fence. It was a thriving market town until two years ago, famous for its nurseries, vegetables and fruits. Now that the fence divides the town from the outside world, the farmers from their land, the populace from their vegetable allotments and water supplies, making citizens dependent on humanitarian aid, it is not surprising that many have emigrated to Jordan. Hence the policy of 'voluntary transfer' is already working: the Mayor of Qalqilya reports that up to 20% of its citizens have already left.

My first trip to Qalqilya, a few months ago, was to visit the hospital's obstetric department. To illustrate the problem of the check-points, the midwife told us of a 17-year-old first-time mother. She had delivered at home, as many Palestinians now must, fearing being stuck at the check-points. She bled badly after the birth. Her father, a paramedic, rang ahead to get an ambulance from Qalqilya to meet them at the check-point, where he thought the soldiers would allow her through to the waiting ambulance. He was wrong: she was not allowed through, and died of a post-partum haemorrhage, the ambulance a few meters away, unable to help.

After seeing the animals, we retreated for lunch: a Palestinian national dish – falafel – from a café on the main square. A van drove past selling gas canisters, ringing out its tinny call-tune. At the falafel café we met a lab technician who can no longer go to his job in a nearby town because he can't get a permit to leave Qalqilya. "Now they are building this wall, they are slowly continuing all the time, flattening everything near it, all the gardens, all the homes. The Israelis have killed everything in Qalqilya. And during Eid they attacked us and killed three, one an eight year-old boy."

As we left, my 9 year-old asked if the ambulance we saw being searched at the check-point would be allowed through or not. I asked the soldiers: they were Russian, and spoke no English. But the two Palestinian ambulance-workers looked at us, and said that yes, they were being allowed through – today. "No problem", they smiled, and went on showing the soldiers the contents of their ambulance. My son turned to me and said, "You know, today was OK, I like animals. But zoos – I don't like zoos at all".

Beyond the concrete enclosures that imprison first the animals and then the people of Qalqilya, the zoo-within-a-zoo analogy ends - the difference is that Israelis don't come and gawp at these inmates. The purpose of the wall and fence is the opposite: to put the inmates out of sight and out of mind, to remove every vestige of livelihood and dignity from them, and preferably, persuade them to leave. Plus, of course, most other zoo-keepers don't shoot their animals.