Israeli Defense Minister Ehud Barak has given the nod to call up 30,000 reservists, as the fighting between Israel and Palestinian militants in the Gaza Strip intensified Thursday, Israeli TV reported.

The legal advisor to the security establishment on Thursday evening sought the government's approval to call up 30,000 troops, the Defense Ministry said in a statement sent to Xinhua.

"All options are on the table in stopping the rocket fire from Gaza into Israel," army spokesman Brig. Gen. Yoav Mordechai told local television outlets.

Barak also said that the rocket fire toward central Israel is " an escalation which the other side will have to pay a price for.

Militants have fired upwards of 270 rockets and mortar shells at Israel since the latter launched a military operation in Gaza, dubbed "Pillar of Defense," on Wednesday afternoon, killing Hamas military chief Ahmed Jabari.

Rocket from Gaza picked up pace in the aftermath of Jabari's assassination and intensified on Thursday, with all major cities in southern Israel and Gaza-border communities coming under heavy barrages. Explosions have been reported as far away as Dimona, some 75 km from the Strip.

Later in the day, rocket attacks expanded to central Israel. Two explosions were heard near Rishon Letzion, south of Tel Aviv. An hour later, air raid sirens wailed in Tel Aviv, the country's largest city and economic hub. It remained unclear whether the projectiles exploded within or near the city.

There were no reports of injuries or damage in the strike, but local media underscored that Tel Aviv's residents had not heard "a real siren" since the 1991 Gulf War.

Local media outlets reported Thursday evening that a ground operation in Gaza could begin as early as Friday. Large forces, including several armored brigades and infantry units are already massed along the border.