The UN agency for Palestinian refugees, or UNRWA, says more than 1 million people have fled Rafah in the southern Gaza Strip in the past three weeks, as Israel continues military attacks in the area.

The agency made the report at a news conference on Tuesday, calling for an immediate ceasefire.

Local officials in Gaza announced that Israeli shelling of a camp for displaced people killed 21 people on the same day.

The Israeli military later issued a statement to deny responsibility, saying it did not strike humanitarian areas.

But international criticism of Israel has been mounting as its airstrikes on Rafah on Sunday reportedly killed 45 people, including women and children.

The US Department of Defense said on Tuesday that humanitarian aid deliveries to Gaza have been suspended as rough weather damaged a floating pier installed by the US military.

The suspension has caused concern that the humanitarian situation in Gaza may further deteriorate.

Aid deliveries to the Palestinian enclave have stalled as the border crossing has been closed since Israel began ground operations in Rafah.