When the calves were hauled out of the tunnel from Egypt on Tuesday, they could hardly stand up.

After a terrifying, 1000 meter (yard) underground trip into the Israeli-blockaded Gaza Strip, what the young cattle wanted most was a long drink of cool water.

Underground livestock smuggling has increased dramatically ahead of Eid Al-Adha, the day of sacrifice due December 10, when Muslims the world over slaughter animals and feed the poor to seek God's forgiveness.

"Even if we brought in animals every day we would not meet the demand for the Eid," said a tunnel operator who identified himself as Abu Luqaib.

Hundreds of Gaza merchants throng around the border area of Rafah every day to pick up merchandise coming to Gaza from Egypt via subterranean passages that have created a flourishing trade zone.

"It's an industrial zone here," said the 23-year-old tunnel operator as his crew pulled a bawling calf up the deep shaft by a simple rope around its middle. No livestock harness was used.

Gaza has suffered galloping unemployment since Israel tightened its blockade on the territory in 2007 to try to weaken its Palestinian rulers, Hamas, an Islamist group sworn to the destruction of the Jewish state.

Goods are scarce in Gaza markets because of Israeli restrictions on what Gaza may and may not import. The tunnel network handles all sorts of readily portable merchandise including fuel, automobile parts, computers and clothes.

TRANQUIL RIDE

The number of tunnels has mushroomed in the past year to around 800, according to Abu Luqaib. They employ between 20,000 to 25,000 workers in a gray economy struggling for survival.

A standard 500 meter tunnel costs $60,000 to $90,000 to build, he says. A 1,000 tunnel built with extra safety features can cost up to $150,000.

The tunnels can be dangerous. Palestinian officials say at least 45 Gazans have died in cave-ins this year, some of which were blamed by Hamas on the security forces in Egypt, who are under pressure from Israel and the United States to clamp down.

But such risks are clearly outweighed by potential profits.

The calves that came through on Tuesday cost $350 each plus $250 for the transport, a total of $600 per head.

Hamas, which seized control of Gaza in 2007 from the secular Fatah movement of Palestinian President Mahmoud Abbas, endorses the tunnels as a way of defying the blockade, and, according to some Gaza residents, imposes taxes on the tunnel trade.

It also keeps a close eye on what comes through.

"No one can smuggle arms or drugs, on the orders of Hamas," said Abu Luqaib. Israel, however, says Hamas runs its own tunnel network to bring arms, explosives and ammunition.

The tunnels also ferry people who cannot otherwise leave or enter Gaza unless they have Israeli or Egyptian permission.

One Gaza woman, Umm Khaled, had been stuck in Egypt for several weeks while her husband fretted over telling her the unwelcome news that her only way home was via a dark tunnel.

So friends slipped a sleeping draught into her glass of juice, wrapped her in a blanket and laid her in an underground trolley to be whisked through to the beleaguered Gaza Strip.

"She got the fastest, most tranquil, and safest trip home in the end," said tunnel operator Ahmed, who gave no second name.