The Israeli military said three soldiers were wounded in an explosion Thursday in a "booby-trapped shaft" in Rafah, the south Gaza city where troops launched an incursion earlier this week.

"Earlier today (Thursday), three IDF (army) soldiers were moderately injured as a result of the explosion of a booby-trapped shaft in eastern Rafah," the military said in a statement.

"The soldiers were evacuated to the hospital to receive medical treatment," it added.

The announcement came after Israel defied vociferous international opposition to any major military operation in Rafah by sending ground troops into eastern areas of the city in "targeted raids".

Israel says Rafah is the last redoubt of Hamas's remaining fighters but the city on the border with Egypt is also crammed with displaced Palestinian civilians.

US President Joe Biden has threatened to stop some arms deliveries to Israel if it goes ahead with a full-scale assault on Rafah, where the UN says 1.4 million people are sheltering.

The Gaza war began with Hamas's unprecedented October 7 attack on Israel, which resulted in the deaths of more than 1,170 people, mostly civilians, according to an AFP tally of Israeli official figures.

Militants also seized some 250 hostages, of whom Israel estimates 128 remain in Gaza, including 36 officials say are presumed dead.

Israel's retaliatory offensive has killed at least 34,904 people in Gaza, mostly women and children, according to the Hamas-run territory's health ministry.