Three US military cargo planes air-dropped food into the besieged Gaza Strip on Saturday, an American official said, as the coastal territory faces a growing humanitarian crisis after months of war.

"We conducted a combined humanitarian assistance air drop into Gaza" involving three US Air Force C-130s to provide "relief to civilians affected by the ongoing conflict," a US Central Command official told AFP on condition of anonymity.

The planes dropped "66 total bundles of pork-free meals" on Saturday afternoon local time, the official said, adding that a tonnage figure is not currently available.

President Joe Biden announced the previous day that the United States would start to deliver relief supplies from the air into Gaza, after the deaths of more than 100 Palestinians at an aid convoy on Thursday.

In that incident, dozens of desperate Palestinians were killed rushing a convoy in northern Gaza, which has been under siege since Hamas's October 7 attack on Israel, and where the UN has warned of famine.

Biden has pushed Israel to reduce civilian casualties and allow aid in, while at the same time he has maintained military assistance for the key US ally.

US National Security Council spokesman John Kirby said Friday that the United States planned to carry out multiple air drops that would last weeks.

He described it as a "tough military operation" that required careful planning by the Pentagon for the safety of both Gazan civilians and US military personnel. (AFP)