Israeli troops and tanks pushed on Saturday into parts of a congested northern Gaza Strip district that they had previously skirted in the more than seven-month-old war, killing and wounding dozens of Palestinians, medics and residents said.

Israel's forces also took over some ground in Rafah, a southern city next to the Egyptian border that is packed with displaced people and where the launch this month of a long-threatened incursion to crush Hamas hold-outs has alarmed Cairo and Washington.

Israel has conducted renewed military sweeps this month of parts of northern Gaza where it had declared the end of major operations in January. At the time, it also predicted its forces would return to prevent a regrouping by the Palestinian Islamist group that rules Gaza.

One site has been Jabalia, the largest of Gaza Strip's eight historic refugee camps. On Saturday, troops and tanks edged into streets so far spared the ground offensive, residents said. In one strike, medics said 15 Palestinians were killed and dozens wounded.

The Gaza health ministry and the Civil Emergency Service said teams received dozens of calls about possible casualties but were unable to carry out any searches because of the ongoing ground offensive and the aerial bombardment.

"Today is the most difficult in terms of the occupation bombardment, air strikes and tank shelling have going on almost non-stop," said one resident in Jabalia, Ibrahim Khaled, via a chat app.

"We know of dozens of people, martyrs (killed) and wounded, but no ambulance vehicle can get into the area," he told Reuters.

The Israeli military said forces have continued to operate in areas across the Gaza Strip including Jabalia and Rafah, carrying out what it called "precise operations against terrorists and infrastructure".

"The IAF (air force) continues to operate in the Gaza Strip, and struck over 70 terror targets during the past day, including weapons storage facilities, military infrastructure sites, terrorists who posed a threat to IDF troops, and military compounds," the military said in a statement.

Armed wings of Hamas, the Islamic Jihad, and Fatah said fighters attacked Israeli forces in Jabalia and Rafah with anti-tank rockets, mortar bombs, and explosive devices already planted in some of the roads, killing and wounding many soldiers.

Israel's military said 281 soldiers have been killed in fighting since the first ground incursions in Gaza on Oct 20.

At least 35,386 Palestinians have been killed in Israeli strikes since Oct. 7, according to figures from the enclave's health ministry, while aid agencies have warned repeatedly of widespread hunger and dire shortages of fuel and medical supplies.

In the Hamas attack on Oct. 7, 1,200 people died in Israel and 253 were taken hostage, according to Israeli tallies. About 125 people are still being held in Gaza.

In Rafah, where Israeli tanks thrust into some of the eastern suburbs and clashed with Palestinian fighters there, residents said Israeli bombing from the air and ground persisted all night.

Rafah had been sheltering more than one million displaced Gazans. UNRWA, the main U.N. aid agency for Palestinians, said more than 630,000 people had fled Rafah since the offensive there began on May 6. Israel says it must capture Rafah to destroy Hamas and ensure the country's security.