Gaza's civil defence agency said on Saturday Israeli attacks killed 26 people and wounded more than 100 near two aid centres in the south of the Palestinian territory.

Agency spokesman Mahmud Basal said 22 were killed near a site southwest of Khan Younis and four near another centre northwest of Rafah, blaming "Israeli gunfire" for both.

One eyewitness said he headed to the Al-Tina area of Khan Yunis before dawn with five of his relatives to try to get food when "Israeli soldiers" started shooting.

"My relatives and I were unable to get anything," Abdul Aziz Abed, 37, said. "Every day I go there and all we get is bullets and exhaustion instead of food."

The Israeli military said it was "looking into" the claims.

Deaths of people waiting for handouts in huge crowds near aid distribution centres have become a regular occurrence, with the Palestinian authorities blaming Israeli fire.

The civil defence agency reported that nine people were shot and killed near the same aid point in the Al-Shakoush area northwest of Rafah on Friday.

The US- and Israel-backed Gaza Humanitarian Foundation (GHF), which took over the running of aid distribution in late May, said 20 people died in Khan Younis on Wednesday.

But it blamed "agitators in the crowd... armed and affiliated with Hamas" for creating "a chaotic and dangerous surge" and firing at aid-seekers.

The previous day, the UN said it had recorded 875 people killed in Gaza while trying to get food, including 674 "in the vicinity of GHF sites", since it began operating.

The free flow of aid into Gaza is a key demand of Hamas in indirect talks with Israel for a 60-day ceasefire in the 21-month war. (AFP)