The stranglehold on aid reaching Gaza threatens an "apocalyptic" outcome, the UN humanitarian chief said on Sunday as he warned of famine in the besieged territory.

"If fuel runs out, aid doesn't get to the people where they need it, that famine, which we have talked about for so long, and which is looming, will not be looming anymore. It will be present," Martin Griffiths said.

"And I think our worry, as citizens of the international community, is that the consequence is going to be really, really hard. Hard, difficult, and apocalyptic," he told AFP on the sidelines of meetings with Qatari officials in Doha.