The Israeli military said it had called up an unprecedented 300,000 reservists and was imposing a blockade on the Gaza Strip, in a sign it may be planning a ground assault in response to the devastating weekend attack by Hamas gunmen.

Israeli TV channels said the death toll from the Hamas attack had climbed to 900. Gaza's Health Ministry said at least 687 Palestinians have been killed in Israeli air strikes on the blockaded enclave since Saturday.

ISRAEL TARGETS GAZA

* After hours of intense bombardment by Israeli jets, Hamas, the Islamist movement which controls Gaza, said it would execute an Israeli captive for every civilian house bombed without warning.

* The spokesperson for Hamas' armed wing said the group will not negotiate over Israeli captives "under fire". The spokesperson, Abu Ubaida, said in a video speech that Israel should be ready to "pay the price" in return for the captives' freedom.

* The U.S. military is sending in fresh supplies of air defenses, munitions and other security assistance to Israel to help it respond to an unprecedented weekend attack by Hamas, a senior U.S. defense official said.

* The U.S. has no intention of putting its military on the ground but will protect U.S. interests in the region, a White House spokesperson said.

* U.S. Chairman of the Joint Chiefs of Staff Charles Brown Jr spoke with the Chief of the Israeli General Staff Herzi Halevi, the Pentagon said, and discussed Hamas' attack and steps to strengthen U.S. military posture in the region.

* The European Union backtracked in disarray on an announcement that aid to Palestinians had been suspended in response to the attack on Israel by Hamas after EU countries complained the bloc's executive had overstepped the mark.

* In a further sign of Israel's rapid shift onto a war footing, a cabinet member from Prime Minister Benjamin Netanyahu's Likud Party said it could set up a national unity government within hours.

*Palestinian President Mahmoud Abbas is expected to visit Moscow, Russian news media quoted the Palestinian envoy to Moscow as saying.

* Israeli shelling on Lebanon killed at least three Hezbollah militants, the group said.

* Qatari mediators have held urgent calls to try to negotiate freedom for Israeli women and children seized by Hamas in Gaza in exchange for the release of 36 Palestinian women and children from Israel's prisons, a source briefed on the talks told Reuters. An Israeli official said no negotiations were under way.

AMERICANS, BRITONS DEAD OR MISSING

* U.S. President Joe Biden said on Monday that at least 11 American citizens were among those killed in Israel. Washington believes it is likely U.S. citizens are also among those being held hostage by Hamas, he said in a statement.

* More than 10 Britons are feared dead or missing in Israel, the BBC reported, citing an official source, although foreign minister James Cleverly said he would not speculate on the number of British or dual nationals in the area.

INSIGHT, ANALYSIS

* Hamas carried out a careful campaign of deception to pull off its stunning attack, accounts from Hamas and Israeli sources show.

* Biden and Netanyahu, uncomfortable allies in the best of times, will put their relationship to the test with Israel preparing a possible ground assault on the Gaza Strip.

GLOBAL MARKETS ROILED

* Oil prices jumped more than 4%, gold gained and the safe-haven U.S. dollar edged up against the euro as military clashes between Israel and the Palestinian Islamist group Hamas fueled some worry that the conflict could spread beyond Gaza.

* Tech companies operating in Israel were expected to fortify security as they could face disruptions, said investors and analysts.

* Major international air carriers suspended or reined in flight services to or from Tel Aviv.