U.S. Vice President Kamala Harris bluntly called out Israel on Sunday for not doing enough to ease a "humanitarian catastrophe" in the Gaza Strip as the administration of U.S. President Joe Biden faces increasing pressure to rein in its close ally while it wages war with Hamas militants.

Harris, speaking in front of the Edmund Pettus Bridge in Selma, Alabama, where state troopers beat U.S. civil rights marchers nearly six decades ago, called for an "immediate cease-fire" in Gaza and urged Hamas to accept a deal to release hostages in return for a six-week cessation of hostilities.

But she directed the bulk of her comments at Israel in what appeared to be the sharpest rebuke yet by a senior leader in the U.S. government over the conditions in the coastal enclave.