Israeli officials say the army will carry out more air raids on the Gaza Strip overnight and call up 1,500 military reservists, as the country moves closer to its third major offensive in the Palestinian territory in six years.

Lieutenant-Colonel Peter Lerner, a spokesman for the Israeli army, tweeted late on Monday that the military had launched "Operation Protective Edge" and would be targeting the Palestinian faction Hamas.

Israeli raids were reported all over the Gaza Strip, including Gaza City, with jets attacking empty training camps belong to Palestinian fighting groups.

Palestinian officials said two air strikes were launched before dawn against homes in southern Gaza. Medics said nine people suffered shrapnel injuries.

Israeli planes also dropped leaflets in the north of the Gaza Strip calling on residents to inform on fighters.

Israel's security cabinet met earlier on Monday after nine people were killed overnight in Gaza, governed by Hamas, and nearly 40 rockets and mortars were fired into southern Israel.

Late on Monday, there was another barrage of at least 20 rockets from Gaza into Israel.

The Qassam Brigades, the military wing of Hamas, which blamed Israel for the loss of seven members overnight, claimed responsibility for the latest salvo.

Israeli government sources said the cabinet agreed on an escalation, but stopped short of authorizing a bombing campaign like the one Israel carried out in 2012, or a ground offensive like the 2008-09 war which left more than 1,400 Palestinians dead.

Sami Abu Zuhri, a Hamas spokesman, accused Israel of a "grave escalation" and warned that it would "pay the price".

'Fiddling with explosives'

Earlier, Lerner denied that the Qassam Brigades fighters were killed in an Israeli air strike, saying they died while "fiddling with explosives" in a tunnel that Israel bombed last week.

Hamas maintained that they were killed by Israel, and regardless, the group has threatened to respond.

The Qassam Brigades posted a message on its Hebrew-language Twitter account, which had been dormant for eight months, warning that Israel should expect heavy casualties should it escalate in Gaza.

"The Zionist enemy should expect that its next war in Gaza will give the name 'a pleasant stroll' to the previous wars, because its losses will be beyond expectations," the group said.

Politicians and analysts say Netanyahu does not want a major escalation.

The mobilization announced on Monday is small: In 2012, for example, Israel called up about 50,000 soldiers.

But Netanyahu is facing mounting pressure to launch a larger offensive, both from residents of southern Israel and from within his own coalition.

Egypt has been mediating between Israel and Hamas, much as it did during the 2012 war.

Sources in Gaza said Hamas has demanded an easing of the siege of Gaza as a condition for stopping the rocket fire.

That could mean concessions from Israel, or an opening of the Rafah crossing with Egypt, neither of which appear likely.

Lieberman withdrawal

The Israeli government has sealed off Gaza for decades. The blockade intensified in 2007, after Hamas took control of the territory following an electoral victory.

The military-led government that came to power in Egypt last year destroyed the vast majority of the smuggling tunnels between Gaza and Sinai and shut the Rafah crossing, cutting off vital lifelines to the outside world.

Against this backdrop of escalating tensions, Avigdor Lieberman, Israel's foreign minister, announced on Monday the end of an 18-month-old unity pact between his party, Yisrael Beiteinu, and Netanyahu's Likud party.

The two men have clashed openly over Gaza in recent days, with Lieberman urging a full invasion of the territory.

"It's no secret. I'm afraid the recent disagreements between the prime minister and myself have become fundamental, and no longer allow the existence of a common framework," Lieberman announced in the Knesset.

"But this coalition will continue, because there is no better alternative."

Lieberman's move does not jeopardize the ruling coalition: it is meant largely to position himself for the next election.

Still, it gives him more space to criticize Netanyahu, adding to the pressure on the prime minister to escalate in Gaza.

"Lieberman plays on the same ground where Netanyahu stands. He's moving from extreme right to the center," Menachem Klein, a political science professor at Bar-Ilan University, said.

"He wants to take the leadership of this camp."

PHOTO CAPTION

Israeli soldiers ride atop a tank outside the southern Gaza Strip July 7, 2014.

Aljazeera