Iran on Monday rejected as unfounded allegations it had a role in the massive assault on Israel by the Palestinian Islamist group Hamas.

"The accusations linked to an Iranian role... are based on political reasons," foreign ministry spokesman Nasser Kanani told reporters, adding that Palestinians had "the necessary capacity and will to defend their nation and recover their rights" without any help from Tehran.

Israel's defense minister ordered Monday a "complete siege" on the Gaza Strip following an unprecedented incursion into Israel by Hamas fighters.

Israel formally declared war on Sunday and gave the green light for "significant military steps" to retaliate against Hamas for Saturday's surprise attack. More than 1,100 people have been killed and thousands wounded on both sides.

Supporters of Israel and backers of the Palestinian cause held competing rallies in several American cities Sunday over the conflict that has killed hundreds and wounded thousands in the Middle East.

In New York City, a skirmish broke out between opposing demonstrators near the United Nations compound after a large group of Palestinian supporters rallied in Times Square. Palestinian Americans protested outside the Israeli consulates in Atlanta and Chicago. Former House Speaker Nancy Pelosi led a Jewish community gathering to support Israel at a synagogue in San Francisco.

Defense Secretary Lloyd Austin said he has ordered the Ford carrier strike group to sail to the Eastern Mediterranean to be ready to assist Israel after the attack by Hamas that has left more than 1,000 dead on both sides. Americans were reported to be among those killed and missing.

The USS Gerald R. Ford, the Navy's newest and most advanced aircraft carrier, and its approximately 5,000 sailors and deck of warplanes will be accompanied by cruisers and destroyers in a show of force that is meant to be ready to respond to anything, from possibly interdicting additional weapons from reaching Hamas and conducting surveillance.

The U.N. Security Council has held an emergency meeting behind closed doors, with the United States demanding all 15 members strongly condemn "these heinous terrorist attacks committed by Hamas," but they took no immediate action.

U.S. deputy ambassador Robert Wood said afterward that "a good number of countries" did condemn the Hamas attack but not all council members. He told reporters they could probably figure out one of them.

Israel's military scoured the country's south for Hamas fighters and guarded breaches in its border fence with tanks on Monday, as it pounded the Gaza Strip from the air and mustered for a campaign its prime minister said would destroy "the military and governing capabilities" of the militant group.

More than two days after Hamas launched its unprecedented incursion from Gaza, the military said the fighting had largely died down for now. The attack caught Israel's vaunted military and intelligence apparatus completely off guard, bringing heavy battles to its streets for the first time in decades.

Two Israeli tourists and one Egyptian were killed Sunday by a policeman in Egypt, local media and Israeli authorities said, as war rages for a second day between Israel and Hamas.

An Egyptian official said Sunday that Israel has sought help from Cairo to ensure the safety of dozens of captives and hostages held by Palestinian militants amid the ongoing war between Israel and Hamas.

The official added that Egypt’s intelligence chief had contacted Hamas and the Islamic Jihad group to seek information.

The death toll from strong earthquakes that shook western Afghanistan has risen to over 2,000, a Taliban government spokesman said Sunday. It's one of the deadliest earthquakes to strike the country in two decades.

A powerful magnitude-6.3 earthquake followed by strong aftershocks killed dozens of people in western Afghanistan on Saturday, the country's national disaster authority said.

Israeli soldiers battled Hamas fighters in the streets of Israel's south on Sunday as Israel's retaliation strikes leveled buildings in Gaza.

Hamas fighters, backed by a volley of thousands of rockets, broke through barricades around Gaza early Saturday to rampage through nearby communities in Israel. They took captives back into the coastal enclave, including women, children and the elderly, while Israel's retaliation strikes leveled buildings in Gaza and its prime minister said the country was at war. Israeli media, citing rescue service officials, said at least 300 people were killed, including 26 soldiers. The health ministry in Gaza meanwhile said that at least 313 Palestinians have been killed and 1,990 wounded since the start of fighting.