US President Joe Biden warned Tuesday of a "very, very dangerous" situation without a Gaza ceasefire deal by Ramadan, adding that it was up to Hamas to accept a deal as talks continue in Cairo.

As the US military made its second airdrop of aid to Gaza, Biden also told ally Israel there were "no excuses" for failing to allow more aid into the Palestinian enclave where the UN warns famine is looming.

Biden's comments came as US frustration grows both with Israel over Gaza's aid needs and spiraling civilian death toll, but also with Hamas for stalling on conditions including the release of hostages.

"It's in the hands of Hamas right now," Biden, 81, told reporters as he flew back to the White House from the Camp David presidential retreat in the hills of Maryland.

"The Israelis have been cooperating, the offer (of a ceasefire) is rational. We'll know in a........

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