For over a hundred miles between the heavily guarded Suez Canal Bridge and the main town in northern Sinai, El Arish, the road is deserted at night. No-one is stopping cars or checking documents at the roadblocks and the guard posts are empty.

Only on the final approach to El Arish can the first signs of a military build-up be seen. Two Soviet-era armoured personnel carriers are positioned on either side of the road; around them stand a squad of nervous-looking conscripts, in full battle-gear and protected by rows of sand-bags.

They peer at the vehicles that slow down as they pass but neither do they, or any other security personnel, ask for identification. From the roof of a nearby building, a machine-gunner provides additional security.

Similar outposts have sprung up since early last week in and around El Arish and every couple of miles, all the way to the border with the Gaza Strip at Rafah.

This is just the latest reinforcement of security forces in Sinai over the past 15 months. Since the fall of President Hosni Mubarak's regime early last year, Israel has quietly allowed the Egyptian army to transfer seven battalions into the region near the border, above the force-level allowed in eastern Sinai by the security protocols of the Camp David peace accords.

Two weeks ago, another operation was announced to return security to the chaotic north-eastern corner of the peninsula after the natural gas pipelines to Israel and Jordan, crucial for Egypt's fragile economy, were sabotaged for the 14th time in as many months.

The pipeline explosions have occurred alongside repeated attacks by Bedouin tribesmen - who have joined forces with Islamist terrorists aligned with al-Qaeda - on military outposts and police stations in the region. They have also linked up with Islamic Jihad in the Gaza Strip and have tried to carry out attacks against Israel, including the one near Eilat last August in which eight Israelis were killed, and a rocket attack on Eilat two weeks ago in which no-one was hurt.

So far, the Egyptian reinforcements have failed to re-establish stability in northern Sinai and the forces stationed there last week did not seem about to do so. They were mainly concerned with defending themselves and their positions. The forces remained static in their posts and did not embark on patrols. Their fears were justified last Sunday when, at an outpost by the El Arish airfield, two soldiers were killed and two more wounded in what appears to have been another attack by Bedouin smugglers or members of the Islamist underground.

"It's clear this is just for show," said Mohammed Beticha, a floor-layer in Rafah, "they don't dare to fight the Bedouin or even venture into the hills." In clear view of the soldiers, Bedouin touts continued plying their trade, one of them approaching visitors to the town offering them routes across the border, "overground and underground." Despite all the joint efforts of Israel, Egypt and the US army advisers who were sent to the region two years ago, the smuggling in tunnels beneath Rafah continues apace.

The Bedouin have made it clear to the Egyptian authorities that any attempt to curtail their business will be met with violence and sabotage.

"Israel has no choice but to agree to the Egyptian requests," said a senior Israeli security official. "We have an interest, of course, in them rebuilding security on the border but the fact is that they are not doing it. Meanwhile, the Egyptian army is achieving one of its strategic goals and rebuilding bases near Israel."