The main UN aid agency in Gaza said an Israeli strike a day earlier hit one of its warehouses in the southern city of Rafah, killing an employee, although Israel later said a Hamas militant was killed in the rocket strike.

Donor nations, aid agencies and charities pushed on with efforts to rush food to the territory of 2.4 million people, where famine looms after more than five months of war.

Mediation efforts have so far failed to secure a new truce in the Israeli war on Gaza, and Defence Minister Yoav Gallant vowed again that Israeli forces "will reach every location" in their mission to destroy the Islamist group Hamas.

Israeli forces have carried out a campaign of air strikes and ground operations in Gaza, killing at least 31,272 people, most of them civilians, according to Gaza’s health ministry.

The Spanish charity vessel Open Arms left Cyprus for Gaza on Tuesday, towing a barge with 200 tonnes of aid in the first voyage along a planned maritime corridor to Gaza.

It was moving slowly south off the coast of Israel, according to specialist website Marine Traffic.

However, airdrops and efforts to open a maritime corridor were "no alternative" to land deliveries because they could only provide a fraction of the aid needed, 25 organisations, including Amnesty International and Oxfam, said in a statement Wednesday.

In Gaza City, desperate Palestinians were awaiting the arrival of the Open Arms aid boat.

"They send aid, but when this aid arrives, there's no entity to distribute it," said Gaza City resident Eid Ayub, adding that aid by sea and air "is not enough".

Land routes needed

Cypriot Foreign Minister Constantinos Kombos said on Wednesday a second aid ship "with bigger capacity" was being prepared in Larnaca.

Kombos also hosted a virtual meeting on Wednesday with US Secretary of State Antony Blinken and senior ministers and officials from Britain, the United Arab Emirates, Qatar, the European Union and the United Nations to discuss the maritime corridor.

"The ministers agreed that there is no meaningful substitute to land routes via Egypt and Jordan and entry points from Israel into Gaza for aid delivery at scale," they said in a joint statement.

They also called on Israel to open the port of Ashdod, north of Gaza, for aid deliveries.

Senior officials will gather in Cyprus on Monday for "in-depth" briefings on the corridor, the statement said.

The Israeli military said the UN's World Food Programme had also sent an initial six aid trucks along an alternative land route from southern Israel through a gate in the security fence into northern Gaza on Tuesday.