Israel defied international outcry and pressed ahead with a major offensive into Rafah on Tuesday with Israeli tanks sighted in the city centre for the first time.
The incursion comes hours after Gaza's civil defence said an Israeli strike west of Rafah killed at least 21 people, half of them women.
Israel rejected responsibility for the strike on Tuesday while offering results of a preliminary investigation that contradicts eyewitness accounts over the strike on Sunday.
Algeria said it would draft a UN Security Council resolution "to stop the killing" in Rafah after members met for an urgent meeting on Tuesday.
The United States said the Rafah attack would not prompt a change in policy towards Israel and it did not cross "Biden's red line".
Meanwhile, global condemnation of Sunday's attack continued to pour in as Ireland, Norway and Spain officially recognised the State of Palestine in a major show of European support for Palestinians.