Civil defence spokesman Mahmud Bassal told AFP that 30 people were killed by Israeli gunfire while waiting for aid near the southern Gaza city of Khan Yunis.

The army told AFP that troops "fired warning shots" in the direction "a gathering of Gazans advancing" towards them in the so-called Morag corridor in the south, but added it was "not aware of any casualties as a result".

Bassal said another 20 people were killed and 100 wounded by Israeli fire near the Zikim border crossing in northern Gaza, through which some aid trucks have entered the territory in recent weeks.

An AFP journalist reported seeing at least a dozen bodies brought to northern Gaza's Hamad Hospital, where a medical source said the victims had been killed in the incident near Zikim.

The army told AFP it was looking into the details of the incident.

According to Bassal, six more people were killed and 21 injured by Israeli fire in central Gaza while waiting for food near a distribution centre.

The Israeli army, however, denied having opened fire near any aid site in central Gaza on Tuesday.

Media restrictions in Gaza and difficulties in accessing many areas mean AFP is unable to independently verify the tolls and details provided by the civil defence and the army.

Thousands of Gazans gather daily near food distribution points across Gaza, including four belonging to the US- and Israeli-backed Gaza Humanitarian Foundation.

Since launching in late May, its operations have been marred by near-daily reports of Israeli forces firing on those waiting to collect rations.

Israeli restrictions on the entry of supplies into Gaza since the start of the war nearly 22 months ago have led to shortages of food and essential goods, including medicine and fuel, which hospitals rely on to power their generators.

- 'No safety' -

Bassal said another five people were killed in a predawn air strike on a tent in Al-Mawasi in south Gaza, an area Israeli authorities designated as a safe zone early in the war.

"It's said to be a green zone and it's safe, but it's not. They also say that the aid (distribution) is safe, but people die while obtaining aid," said Adham Younes, 30, who lost a relative in the strike.

"There's no safety within the Gaza Strip, everyone is exposed to death, everyone is subject to injury."

Mahmud Younes, who said he witnessed the strike, told AFP: "We found women screaming -- they were covered in blood. The entire family has been injured."

Bassal also reported six people killed in a strike near Gaza City, and one in another near Khan Yunis.

The Ezzedine Al-Qassam Brigades, Hamas's armed wing, said in a statement Tuesday that they had bombarded an Israeli command-and-control centre in south Gaza's Israeli-controlled Morag corridor.

The army said it had no record of such an attack taking place on Tuesday.