RAFAH, Gaza Strip -- A large Israeli armed force rolled into the Rafah refugee camp on the Gaza-Egypt border early Friday on a mission to destroy tunnels used for smuggling arms, witnesses and military sources said.

Witnesses said a large number of tanks and other armored vehicles entered Rafah from two directions. They were joined by special forces, including engineering units with dogs trained to uncover tunnels.

A military commander at the scene said that weapons smuggled in from Egypt to Gaza eventually make their way to the West Bank, so "we had no choice but to strike deep against the tunnels."

Israeli military sources, speaking on condition of anonymity, said Israel had intelligence warnings that Palestinians were planning to use tunnels under the border to smuggle in weapons that could have a strategic impact on the three-year Israeli-Palestinian conflict, but the Egyptians were not taking steps to stop them.

The Israeli military announced late Tuesday it was extending the lockdown of the West Bank and Gaza, banning Palestinians from Israel and cordoning off Palestinian towns.

Blanket closures, including travel bans within the Palestinian areas, are usually imposed during Jewish holidays, and restrictions are eased -- though not lifted -- once the holidays are over. The most recent one, Yom Kippur, ended Monday, and the next one, the weeklong Succot holiday, begins at sundown Friday.

Lockdown goes on

However, Defense Minister Shaul Mofaz ordered the strict lockdown to continue, reportedly at least through Oct. 22, or several days after the end of Succot. Mofaz reportedly went against the recommendations of security officials who said the level of alerts about possible terror attacks was not unusual.

Mofaz also ordered two more battalions -- about 800 soldiers -- sent to the West Bank and Gaza, canceling leaves and training courses for soldiers. Orders for mobilizing reserve soldiers also are being drawn up, the Israeli military said.

Israel has mounted dozens of smaller missions during the conflict, aimed at uncovering and destroying the tunnels, turning the Rafah refugee camp into a constant battlefield. However, the Friday operation was larger in scope because of the threat of the new range of weapons set to be smuggled, the sources said.

The sources said Palestinians were attempting to acquire missiles that could knock out tanks and aircraft, weapons they have not used up to now. These would include Stinger shoulder-mounted anti-aircraft missiles that could shoot down the attack helicopters Israel often uses in operations in Gaza, the sources said.

Stinger missiles could also threaten Israeli warplanes or civilian aircraft flying close to Gaza.

Also, the sources said, the Palestinians were trying to smuggle Katyusha rockets, which would have the range to hit Israeli cities near Gaza. During the conflict, the Palestinians have been aiming homemade mortars and rockets at Israeli towns and settlements.