CAIRO/JERUSALEM (Reuters) - Israel's tanks pushed into the heart of Jabalia in northern Gaza on Thursday, facing anti-tank rockets and mortar bombs from militants concentrated there, while in the south, its forces pounded Rafah without advancing, Palestinian residents and militants said.

The slow progress of Israel's offensive, more than seven months after it was prompted by Hamas' deadly cross-border raid, highlighted the difficulty of achieving Prime Minister Benjamin Netanyahu's aim of eradicating the militant group.

Armed wings of Hamas and its ally Islamic Jihad have been able to fight up and down the Gaza Strip, using heavily fortified tunnels to stage attacks in both the north - the focus of Israel's initial invasion - and new battlegrounds like Rafah.

Israel says four Hamas battalions are now in Rafah along with hostages abducted during the Oct. 7 assault, but faces pressure from the United States, Europe and the United Nations not to invade the city, where hundreds of thousands of displaced Palestinian civilians are sheltering.

"The operation in Rafah is still limited in space and in targets," military spokesperson Lt. Col. Nadav Shoshani said on Thursday, adding that its attacks were based on specific intelligence about militant activity.

More than 35,000 Gazans have already been killed, according to health officials in the Hamas-run coastal enclave and malnutrition is widespread as international aid efforts are blocked by the violence.

Israel says it needs to wipe out Hamas for its own protection after the deaths of 1,200 people on Oct. 7, and to free the 128 hostages still held out of 253 abducted by the militants, according to its tallies.

The United States anchored a temporary floating pier to a beach in Gaza on Thursday to boost aid deliveries, but it was still unclear how it would be distributed given the challenges that have beset the United Nations and relief groups for months.

MAIN MARKET IN JABALIA UNDER FIRE, RESIDENTS SAY

Israel declared major operations over in northern Gaza months ago while pledging to return to prevent Hamas regrouping.

On Thursday, around a week after they moved back in, Israeli tanks were heavily bombarding the main market in the heart of Jabalia, a decades-old refugee camp, and several stores there caught fire, residents and Hamas media outlets said.

Earlier, the armed wing of Hamas said its fighters in Jabalia had destroyed an Israeli troop carrier with a locally-made Al-Yassin 105 anti-tank rocket, leaving members of the crew dead and wounded. Reuters was not immediately able to verify the statement and there was no immediate comment from Israel.

"They are bombing like crazy, destroying the houses and the main market in the camp," one of the camp's residents told Reuters via a chat app.

"It seems they are acting this way because of the resistance operations that grilled their soldiers," he added, refusing to give a name for fear of reprisals.

Residents said tanks had also pushed back to near the entrance to the nearby northern city of Beit Hanoun and Israeli bulldozers were demolishing factories and property in the area.

Palestinian medical teams said they were aware of reports of casualties in Jabalia but were unable to reach them because of the intensity of Israeli bombing and the active army incursion.

Among those killed were a Palestinian journalist, Mahmoud Jahjouh, and his family, medics and fellow journalists said.

Israeli says it has eliminated many gunmen in Jabalia but had no new comment on developments there on Thursday morning.

In Gaza City to the south, medical teams and the Civil Emergency services said they were continuing the search for casualties in the suburbs of Zeitoun and Sabra after dozens of bodies were recovered in the wake of a six-day army raid there. Palestinian authorities do not distinguish between militants and civilians when reporting death tolls.

In the southern tip of Gaza, tanks held their positions in eastern neighbourhoods and outskirts of Rafah while keeping up pressure with aerial and ground bombardments.

Medics said one Israeli tank shell had landed in a square deep inside Rafah, killing one Palestinian and wounding several others, while residents said clusters of homes on the edge of the city to where Israel has told civilians to evacuate had been blown up by the army.

They said heavy tank shelling struck three homes in the Brazil suburb of eastern Rafah, while medics reported that an airstrike on the edge of the city of Khan Younis further north had killed and wounded several people.

Israel said its strikes were targeted at militants.

"We're operating in specific places according to our intelligence and where we know Hamas terrorists are hiding, and where we think we can find either tunnel shafts or terror infrastructure or ammunition of many types," Shoshani said.

"And we found a lot of anti-tank missiles ... and are trying to prevent the next shooting towards Israeli civilians from that area," he added.

(Reporting by Nidal al-Mughrabi in Cairo, Ari Rabinovitch in Jerusalem; writing by Philippa Fletcher; editing by Ros Russell)

By Nidal al-Mughrabi and Ari Rabinovitch