WRAPUP 13-Israel on war footing, Hamas threatens to kill captives

(Adds Israeli wounded, foreign nationals among the dead, Human Rights Watch comment, paragraphs 4,5,9)

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LATEST DEVELOPMENTS

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900 Israelis and 687 Palestinians dead with thousands injured

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Hezbollah says at least three members killed in Israeli fire

By Nidal al-Mughrabi and Dan Williams

GAZA/JERUSALEM, Oct 9 (Reuters) - The Israeli military said on Monday it had called up an unprecedented 300,000 reservists and was imposing a total blockade of the Gaza Strip, in a sign it may be planning a ground assault in response to the devastating weekend attack by Hamas gunmen.

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

Inside Israel, Palestinian fighters were still holed up in several locations, two days after they killed hundreds of Israelis and seized dozens of hostages in a raid that shattered Israel's reputation of invincibility.

Israeli TV channels said the death toll from the Hamas attack had climbed to 900, with at least 2,600 injured. Gaza's Health Ministry said at least 687 Palestinians had been killed and 3,726 wounded in Israeli air strikes on the blockaded enclave since Saturday.

The dead included citizens of Italy, Ukraine and the United States, where President Joe Biden announced on Monday that at least 11 Americans had been killed.

Hamas spokesman Abu Ubaida said the group had been acting in accordance with Islam by keeping the Israeli captives safe but issued the threat to kill civilians and broadcast it.

Echoing Hamas, the Islamic Jihad armed wing, which said it was holding more than 30 Israelis, asked Israel to refrain from hitting civilians if it cared about the fate of Israelis in its custody.

In Gaza, as Israel conducted intense retaliatory strikes, Defence Minister Yoav Gallant drew international condemnation by announcing a tightened blockade to prevent food and fuel from reaching the strip, home to 2.3 million people.

"Depriving the population in an occupied territory of food and electricity is collective punishment, which is a war crime," Omar Shakir, Israel and Palestine Director at Human Rights Watch, said in a statement.

The Israeli air strikes became more aggressive as night fell, and witnesses said several Hamas security headquarters and ministries were hit. The strikes destroyed some roads and houses.

Israel also bombed the headquarters of the private Palestinian Telecommunication Co., which could affect landline telephone, internet and mobile phone services.