Humanitarian assistance has begun to arrive in Gaza along a US-made pier, but the US aid chief said the new sea corridor could not be a substitute for land crossings, and warned that deliveries of food and fuel entering Gaza had slowed to “dangerously low levels”. The White House national security spokesperson, John Kirby, confirmed on Friday that truckloads of humanitarian aid, including food from the United Arab Emirates, sent by ship from Cyprus, had been unloaded on the Gaza coast and handed over to the control of the UN. Kirby told reporters at a White House briefing: “Hopefully by the time we’re done here, some of that stuff will actually be in the mouths of some hungry people.” The Associated Press, however, quoted an unnamed UN official as saying distribution of the shipment had not begun as of Friday afternoon. The UK said the aid delivery unloaded on Friday also included 8,400 kits to provide temporary shelter made of plastic sheeting. The head of the US Agency for International Development (USAid), Samantha Power, said the US would use the sea route to deliver “metric tons of life-saving aid, including nutrient rich food to support thousands of Gaza’s most vulnerable children and adults; and critical supplies such as plastic sheeting for shelter, jerry cans to hold clean water, and hygiene kits”. But, Power added: “The pier that opened today does not replace or substitute for land crossings into Gaza, every one of which needs to operate at maximum capacity and efficiency. Every moment that a crossing is not open, that trucks are not moving, or where aid cannot safely be distributed, increases the terrible human costs of this conflict. “In the past two weeks, food and fuel entering Gaza has slowed to dangerously low levels – barely 100 trucks of aid a day entered Gaza, far less than the 600 needed every day to address the threat of famine,” Power warned. “Much more must be done to save lives and alleviate the widespread suffering.” Israeli military operations around the southern city of Rafah have led to the closure of a nearby crossing point from Egypt, and the interruption of almost all land deliveries through another southern gate at Kerem Shalom. Meanwhile, trucks heading for the northern crossing at Erez have been ambushed and looted by Israeli extremists in recent days, with little attempt by the police to protect the convoys. Although the Israel Defense Forces (IDF) have yet to launch an attack on the centre of Rafah, the UN said on Friday that nearly 640,000 people had been displaced from the city, many of them going north to Deir al-Balah, where, it said, conditions were “dire”. The maritime route involves shipments of aid being inspected by Israel at the Cypriot port of Larnaca, then transported by large ships to a floating dock a few kilometres off the Gaza coast. There, aid pallets are loaded on to trucks that are taken by smaller vessels into the shallow coastal waters; then the trucks drive on to a floating, 500-metre causeway to a marshalling yard dug in to the sand. The capacity of the route is intended to be 90 truckloads of international aid into Gaza each day, eventually building up to 150 truckloads a day. The aid is formally handed to the World Food Programme on the coast, but it is unclear how it will be distributed around Gaza. It would have to pass through an Israeli checkpoint to reach northern areas where famine is most severe. Renewed fighting was reported in the northern areas on Friday, as Israeli tanks and planes took part in an assault on the Jabalia refugee camp in northern Gaza. Residents said that Israeli armoured vehicles had reached as far as the market in the town, and had thrust as far as the market at the heart of Jabalia, which the IDF had previously claimed had been cleared of Hamas fighters. The reports said bulldozers were demolishing homes and shops in the path of the Israeli advance. “Tanks and planes are wiping out residential districts and markets, shops, restaurants, everything. It is all happening before the one-eyed world,” Ayman Rajab from western Jabalia was quoted as saying by Reuters. Late on Friday, one person was killed and eight injured in an Israeli airstrike on the West Bank city of Jenin, the Palestinian health ministry said. The IDF said a fighter jet had targeted a building in Jenin as part of a counter-terrorism operation against “a terrorist squad that was under surveillance and planned an attack in the near future”. The Guardian could not independently verify the claim. Meanwhile, Kirby said that 17 doctors with US citizenship who had been trapped in Gaza were able to leave on Friday. Twenty doctors were initially reported to be stuck inside the coastal strip. “I won’t speak for the other three, but I can assure you that any of them that wanted to leave are out now,” Kirby said. Power said that the US was leaning on Israel to ensure there would be no repeat of the bombing of an aid convoy on 1 April, in which seven workers for the World Central Kitchen were killed. “In light of unconscionable attacks on aid workers since the war began, we will continue to press the Israeli government to protect civilians and humanitarian workers,” she said in a written statement. Kirby insisted, however, that the White House was not concerned about Israel bombing the aid coming through the maritime corridor. “We are not worried about the Israelis striking the convoys of trucks that are coming off of that pier,” he said. “They are actually participating in helping marshal that material ashore, and then get it into Gaza. So that’s not a concern.” The US national security adviser, Jake Sullivan, is expected to travel to Saudi Arabia on Saturday for talks with the crown prince, Mohammed bin Salman, followed by a stop in Israel for a meeting with the prime minister, Benjamin Netanyahu. Kirby said Sullivan would restate US opposition to a large-scale Israeli assault on Rafah, and would continue to press for more targeted operations against Hamas.