Israeli attacks on Gaza have killed 29 people, including six children and four women, the health ministry in the besieged Palestinian enclave said.

The ministry also said that 253 people in Gaza had been wounded since the hostilities with Israel broke out on Friday.

An Israeli air strike killed a senior commander in the Palestinian Islamic Jihad group, the fighters said on Sunday, their second leader to be slain amid an escalating cross-border conflict.

The violence is the worst in Gaza since a war last year that devastated the impoverished territory.

Israel said it launched the attacks in what it described as the pre-emption of an attack by Palestinian Islamic Jihad attack meant to avenge the arrest of a group leader in the occupied West Bank.

About 2.3 million Palestinians are packed into the narrow coastal Gaza Strip, with Israel and Egypt tightly restricting the movement of people and goods in and out of the enclave.