At least 1,055 people have now been confirmed killed and over 5,000 others injured in Israeli airstrikes on the blockaded Gaza Strip, its Health Ministry confirmed Wednesday.

"We have at least 1,055 martyrs and 5,184 people suffering from different injuries," the ministry said in an update on casualties.

At least 30 people were killed and hundreds wounded as Israel pounded the Gaza Strip with hundreds of airstrikes overnight, a Hamas official said Wednesday.

The strikes destroyed several buildings of the Islamic University in Gaza City, a university official said.

The Israeli military confirmed it had hit dozens of Hamas targets during the night.

It said fighter jets destroyed "advanced detection systems" that Hamas used to spot military aircraft.

Israel has pounded neighborhood after neighborhood in the densely populated coastal enclave, home to nearly 2.2 million people, since Sunday.

The attack came in response to a surprise incursion of Israeli towns near the seaside territory by the Palestinian resistance group Hamas early Saturday.

At least 1,200 people were reportedly killed in Israel and around 2,700 others injured, the military claimed on Wednesday morning.

Israel has also placed a total siege on the enclave, already reeling under a crippling Israeli blockade since 2007.