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Abu Mohammad's journey home took half an hour, but seemed like the longest of his life.
The 22-year-old Palestinian was stranded in Egypt with hundreds of others after the militant group Hamas seized the Gaza Strip in June.
With the overland crossing closed, Abu Mohammad decided to go
underground through one of dozens of tunnels that crisscross the frontier between Egypt and Gaza, run by gangs that smuggle everything, including weapons, people and contraband goods.
He paid a smuggler US$4000 ($5227) to use his tunnel to go home, along with a cargo of bootleg cigarettes.
"It took me about half an hour to crawl back but I thought it was a year," said Abu Mohammad, who spoke on condition that his real name not be used because of his clandestine passage.
"I crawled on my stomach like a snake, I could not raise my head the whole time," he said.
Israel declared the Gaza Strip an "enemy entity" last month and the flow of people and commercial goods through border terminals has been cut sharply since Hamas, shunned by the West for refusing to recognise the Jewish state, took control.
That has translated into steep price hikes for the territory's 1.5 million inhabitants and huge profits for smugglers and the clans who dig the tunnels.
"There has been an increase in demand especially since June," said Abu Salman, a veteran tunnel builder. "Many other tunnels are being constructed."
Abu Salman said each tunnel was built with several shafts so that if one opening was blocked by Israeli forces raiding Gaza or by the Egyptians, smuggling could continue.
Now that Israeli forces have left their positions in the coastal territory - while continuing to mount frequent incursions to target militants - tunnel-diggers are able to break ground closer to the Egyptian frontier.
"We bring in cigarettes, car engines, fertiliser and medicine, including Viagra," said Abu Salman, 35.
The fertiliser, he said, could be used to make explosives.
Gazans began building tunnels in the early 1980s to smuggle in goods from Egypt. Palestinian militant factions took advantage of the underground route to bring in weapons in the 1990s to fight Israeli occupation and build up their power base.
In the years preceding its 2005 Gaza pullout, the Israeli Army has blown up dozens of tunnels - but is powerless to cut the cross-border connection completely.
Guns were now so plentiful in Gaza that once-lucrative weapons smuggling had all but dried up, Abu Salman said.
"I think we have the ability to sell [guns] to Egypt now, not to buy from them."
The real money was in commercial goods, Abu Salman said, estimating a tunnel-owner could make at least US$50,000 for three shipments a month to Gaza merchants.
Abu Salman, who employs 10 diggers, said he had allowed only a few stranded Palestinians to use the 800m tunnel that he built under his family home.
"It is not open to just anyone - only those we trust fully, because we do not want to burn our business," he said.
Tunnel-building is a dangerous and tough job, and several diggers have died in collapses in recent years.
But, Abu Salman said, Gazans "want to do anything for money and to feed their families".
- Reuters