Gaza's Hamas rulers have ordered residents to shut smuggling tunnels along the border with Egypt indefinitely, cutting off the economic lifeline for 1.5 million Palestinians in the impoverished territory, residents and tunnel operators said Wednesday.

Forces of the Islamic militant Hamas moved into the border area late Tuesday and ordered tunnel operators to cease operations until further notice. The operators were allowed to retrieve food and other perishable goods, but otherwise barred from the area on Wednesday.

"This is the first time this has happened," said Jasser Younes, a 25-year-old tunnel worker who helps smuggle cement into Gaza. Two other tunnel operators said Hamas security forces warned people they would be punished if they defied the order. They declined to be identified for fear of punishment.

A Hamas security official confirmed the closure. He spoke on condition of anonymity because he was not authorized to speak to the media.

Hamas has long controlled the tunnel industry and it was not clear why it was suddenly ordering them shut, given their importance to the economy. Israel and Egypt have maintained a tough blockade of Gaza since Hamas seized power nearly three years ago, and the hundreds of tunnels in the Rafah area are the main entry point for many basic items, as well as weapons.

It was also not known whether the closure was connected to an Israeli warning late Tuesday to all citizens in Egypt's Sinai Peninsula to leave immediately, citing "concrete" evidence that militants were trying to kidnap Israelis. By midday Wednesday, most of the estimated 650 Israelis in Sinai had returned.

The Gaza-Egypt border sits at the northeastern tip of the Sinai desert. The Red Sea resort beaches of Sinai, a popular vacation spot for Israelis and other foreign tourists, are on the southeast coast roughly 200 miles (300 kilometers) from Rafah and near a border crossing between Israel and Sinai.

Hamas has been holding a captive Israeli soldier for nearly four years, and it has repeatedly threatened to carry out further kidnappings.

Wednesday's crackdown comes at a difficult time for the tunnel industry.

Rafah officials say that Egypt has stepped up a crackdown on smuggling in recent months, setting up checkpoints in the border area and confiscating contraband. Egypt is also building an underground steel wall to block the tunnels.

Rafah officials say about six kilometers (four miles) of the wall — covering roughly half of the border area — is already complete.

The officials say the Egyptian measures have led to a sharp slowdown in tunnel traffic in recent months, pinching the local economy.