Far from the uproar of Cairo's Tahrir Square, Israel has been doubling its efforts to erect a giant, impenetrable security barrier along its 240-kilometre (150-mile) border with the Egyptian Sinai.

Work on the new border fence began a year ago, in a project initially aimed at stemming the growing tide of economic migrants and asylum seekers from Africa, as well as clamping down on drug trafficking.

But the pace of work has sped up since August, when gunmen from Sinai sneaked across the border and staged a series of deadly ambushes in Israel's southern Negev desert, putting security firmly at the top of the agenda.

"In a month's time, we will have built 100 kilometres of the barrier which by the end of 2012, will extend some 240 km along the border," a senior military officer in the southern command told AFP.

When completed, the fence will stretch the entire length of Israel's desert frontier with Egypt, starting from the Red Sea resort town of Eilat in the south and ending at the Kerem Shalom crossing in southern Gaza.

"For us, it is still a border of peace," he said, pointing to the carcass of a bus which was strafed with gunfire during the August 18 attacks, a series of coordinated ambushes by gunmen who attacked route 12 in the Netafim area, some 20 kilometres north of Eilat.

Eight Israelis were killed during the attacks, along with seven of the gunmen, and five Egyptian policemen who were accidentally shot dead by Israeli troops as they hunted down the remaining attackers in an incident which sparked a diplomatic crisis between the two countries.

"The joint Israeli-Egyptian inquiry (into the incident) has not yet started but cooperation with our Egyptian counterparts continues through the intermediary in our unit for liaising with foreign armies," he said.

Some 200 metres (yards) away, some dozen Egyptian policemen dressed in khaki trousers and T-shirts kicked a ball around near a position which is topped by a watchtower painted in the red, white and black of the national flag.

On the Israeli side, bulldozers, cement mixers and jackhammers were hard at work, kicking up a cloud of dust.

All along route 12, the border road which cuts through a landscape of craggy peaks and ravines, the towering barrier is becoming a concrete reality.

At a rate of 800 metres per day, the giant wall is erasing all trace of the old frontier, which was marked by barbed wire strung between wooden poles which was easy to cut through or climb over because it often fell down.

The new frontier is five metres high and topped with metal spikes, with a foundation which reaches another metre down into the rocky soil. In front of it are three rolls of barbed wire piled on top of each other, and the entire structure is bristling with surveillance technology: sensors, radars, antennae and cameras.

Building the new frontier has accounted for 15 percent of the Jewish state's entire annual steel consumption, with the overall cost of the project set to come in at 1.35 billion shekels (270 million euros/$360 million).

"Unfortunately, we cannot prevent firing from the heights overlooking us, but the concrete fortifications along the road will allow drivers to take cover," the officer said.

He believes that route 12, which has been closed since the August attack, will soon be reopened to hikers.

Despite his assurances, the tension is palpable.

The number of troops in the area "has increased considerably" and "battle-hardened" units in armoured-personnel carriers are deployed there, he said.

The army has also increased its rapid response capabilities and upped the number of radar installations and observation posts in the region. Overhead, two surveillance balloons provide an aerial perspective.

For the time being, the border is still porous.

"The Bedouin from the Sinai are benefiting from this," he said. "They receive $3,000 (2,200 euros) for each African migrant they get across."

In 2010, some 14,735 illegal immigrants, mostly Eritreans, crossed the border into Israel, which for them is nothing short of the promised land.

Of that number, only 7 percent were granted the status of asylum seekers.

This year, official statistics show that by early November, 12,407 "infiltrators" had entered Israel, with 950 crossing the border in the first six days of November.

"Israel is a small country. It cannot allow itself to be flooded with illegal economic migrants," Prime Minister Benjamin Netanyahu said last week.

"It is a threat to the society, the economy and to security."

On Sunday, cabinet ministers voted to approve new measures to further clamp down on immigration, including enlarging a desert detention camp at Ketziot near the Egyptian border, expanding its capacity from 2,000 places to 5,500.

The border area is also a paradise for Bedouin smugglers, with the Israeli authorities often seizing drugs, cigarettes and telecommunications equipment -- and even weapons and explosives heading for the Gaza Strip.