ISRAEL'S GROUND OFFENSIVE TO TAKE "MANY DAYS"-ARMY

Hamas's armed wing vowed on Saturday that Israel would pay a "high price" for the ground operation it has launched on the Islamic movements Gaza Strip stronghold, AFP reported.

An SMS message sent by Hamas military wing, Izzedine al-Qassam, said that "the Zionists started approaching the trap which our fighters prepared for them."

OPERATION TO BE LONG
Israel's Gaza offensive, which escalated into a ground incursion on Saturday, will take many days, the chief military spokesman said.

"This won't be a school outing," Brigadier Avi Benayahu told Israel's Channel Two television. "We are taking about many long days."

IDF spokeswoman Maj. Avital Leibovich told CNN that Israeli army had launched the second stage of the operation against Hamas infrastructure.

Leibovich said Hamas militants had launched 20 rockets from Gaza into Israel by late afternoon Saturday.

"We still see that Hamas is targeting Israeli civilians. Namely, we still did not reach the goal of crippling Hamas' launching capabilities," Leibovitch said.

"We still have many more targets to go," she added.

The IDF said that a large amount of Armored Corps, Engineering Corps and Infantry troops entered the territory with the purpose of destroying Hamas infrastructure and preventing rocket fire by taking control of launching pads in northern Gaza.

The IDF warned that "terrorists using civilians as human shields would bear full responsibility for their fate."

Israel aims to "take over" areas in Gaza from where militants have fired rockets into the Jewish state, Prime Minister Ehud Olmert's office said on Saturday after ground troops entered the enclave.

Israel is calling up thousands of reservists to take part in its ground operation against Hamas in Gaza, Defence Minister Ehud Barak's office said on Saturday.

EXCHANGE FIRE
Israeli tanks opened fire on Hamas positions after entering the northern Gaza Strip on Saturday and Hamas forces replied with mortar fire, witnesses told AFP.

Residents in the Gaza town of Beit Lahiya said the tanks opened fire shortly after crossing the border late Saturday.

Israel's Channel 10 TV reported heavy firefights as troops entered the strip. Other local networks broadcast images of troops marching into Gaza after dark.

HAMAS PROMISES "BLOODSHED"
Exiled Hamas leader Khaled Meshaal promised bloodshed if Israeli ground troops enter Gaza.

"As for you, the soldiers of the enemy whose leadership are getting you ready to enter Gaza in a ground attack, you need to know that doom will await you and you will be killed, injured and captured," Meshaal, speaking in Syria, said on the Al Jazeera television network Friday.

Defense officials said around 10,000 soldiers have massed along the border in recent days. Heavy artillery fire in the early evening was intended to detonate Hamas explosive devices and mines planted along the border area before troops marched in.

Israel's goal is considered to be ending Hamas rule or rocket fire or both, Israeli officials previously said.

On Friday Vice Premier Haim Ramon said in an interview on Israeli television, Israel must not end this operation with Hamas in charge of Gaza.

"What I think we need to do is to reach a situation in which we do not allow Hamas to govern," Ramon told Channel One. "That is the most important thing."