WHO representative in the Palestinian territories Reinhilde Van de Weerdt said Gaza’s health system remains in a critical state, with no hospitals currently operating at full capacity.

"Not enough humanitarian aid is entering Gaza, and definitely not enough to allow for a meaningful expansion and restoration of health services," she told reporters in Geneva, speaking from Jerusalem.

She said Israel's approval system for medical and other humanitarian supplies was proving a major bottleneck.

"It is laborious, time-consuming, with no guaranteed results," she said.

Based on the WHO's latest analysis, large volumes of medical supplies wait for clearance for a median of 74 days, said Van de Weerdt, adding that if it is not, "than we start that lengthy, cumbersome process all over again".

She added that the approval system kept changing, with new regulations introduced.

Israel says it is preventing the entry of items that could also have military use as it accuses Hamas -- which carried out the worst-ever attack against Israel on October 7, 2023 -- of plotting further violence.

Van de Weerdt said standard health kits used worldwide had the lowest approval rate, while X-ray machines, sterilisation equipment and spare parts for CT scans and other essential machinery "get rejected regularly".

"In just the last six months alone, one shipment of prosthetics and assistive devices was rejected four separate times," she said.

However, medicines move "relatively well", with almost 87 percent approved and one percent rejected, she added.

"It's not one single blockage. It's a system, layered with delay after delay... and on the other side of every one of these delays is a patient who is waiting," she said.

"We need the unimpeded and predicable entry of humanitarian and health supplies into Gaza, at scale.

"We hope that Israel will at least release the pressure on medical supplies."

Van de Weerdt called for more crossings into the territory to be opened, and for "clear, published guidance" on processes and requirements.

She added that success should not be measured in terms of numbers of trucks crossing the border, insisting that it says "almost nothing about whether people's actual health needs are being met".

"A truck full of non-priority supplies, or the right supplies arriving too late, doesn't save lives."

The Gaza war was sparked by Hamas's unprecedented 2023 attack against Israel, which resulted in the deaths of 1,221 people, according to an AFP tally based on official Israeli figures.

The massive Israeli offensive in response has left most of Gaza in ruins and killed more than 74,000 people, according to Gaza's health ministry, which is under Hamas authority and whose figures are considered reliable by the United Nations.