Fierce Israeli tank fire and aerial bombing struck Khan Younis in the Gaza Strip on Friday night, residents said, after nearly 200 people were reported killed in 24 hours in Israel’s campaign against Hamas militants.

The sound of shooting indicated fighting between Israeli forces and Hamas fighters in Khan Younis, some residents said. Planes also carried out a series of air strikes on the Nuseirat camp in the central Gaza Strip, according to medics and Palestinian journalists.

Israeli forces have been pounding Khan Younis in preparation for an anticipated further advance into the main southern city, swathes of which they captured in early December.

Defence Minister Yoav Gallant said troops were reaching Hamas command centres and arms depots. The Israeli military also said it had destroyed a tunnel complex in the basement of one of the houses of the Hamas leader for Gaza, Yahya Sinwar, in Gaza City.

Twelve weeks after Hamas militants stormed Israeli towns, killing 1,200 people and seizing 240 hostages, Israeli forces have laid much of the Gaza Strip to waste as it pursues its war aim of eradicating the Islamist militants.

Nearly all of Gaza’s 2.3 million people have fled their homes at least once and many are on the move again, often reduced to taking shelter in makeshift tents or huddled under tarpaulins and plastic sheets on open ground.

Gaza health authorities said 187 more Palestinians were confirmed killed in Israeli strikes in 24 hours, raising the toll to 21,507 – about 1 per cent of Gaza’s population. Thousands more bodies are feared to be buried in the ruins of obliterated neighbourhoods.

A Palestinian journalist working for Al-Quds TV was killed along with a number of his family members in an Israeli air strike on their house in the Nuseirat camp in central Gaza Strip, health officials and fellow journalists said.

It brings the toll of Palestinian journalists killed in the Israeli offensive to 106, according to Gaza’s government media office.

The Committee to Protect Journalists (CPJ) said last week that the first 10 weeks of the Israel-Gaza war were the deadliest recorded for journalists, with the most journalists killed in a single year in one location.

Most of the journalists and media workers killed in the war were Palestinian. The report by the US-based CPJ said it was “particularly concerned about an apparent pattern of targeting of journalists and their families by the Israeli military.”

Earlier this month, a Reuters investigation found an Israeli tank crew killed a Reuters journalist, Issam Abdallah, and wounded six reporters in Lebanon on October 13 by firing two shells in quick succession from Israel while the journalists were filming cross-border shelling.

Israel has previously said it has never and will never deliberately target journalists and that it is doing what it can to avoid civilian casualties, but the high death toll has caused concern even amongst its staunchest allies.

The US has called for it to scale down the war in coming weeks and move to targeted operations against Hamas leaders. So far Israel shows no sign of doing so.

Israel on Friday said it facilitated the entry of 49,130 vaccine doses, enough to inoculate almost 1.4 million people against illnesses including polio, tuberculosis, hepatitis, diphtheria, tetanus, whooping cough and meningitis.

The vaccine transfer was coordinated with UNICEF, said a statement from COGAT – the defence ministry agency that coordinates with the Palestinians – in order to prevent the spread of disease in the enclave.

Gaza is almost entirely reliant on food, fuel and medical supplies from the outside, and Israel has limited access apart from at the southern end. International agencies say supplies being let in through Israeli inspections are a small fraction of Gaza’s vast needs.

Last week Israel bowed to international pressure to open a second crossing it said would double the number of supply trucks daily to 200, but just 76 were able to enter on Thursday, according to the United Nations, compared to 500 in peacetime.

An Israeli government spokesman said on Friday it does not limit humanitarian aid and the problem was with its distribution inside Gaza.

• A Reuters report