The strikes were the latest in a day of violence that saw the first Israeli death in nine months from a Palestinian rocket attack from Gaza.

The Hamas militant group says it fired at least 20 rockets, including eight at the town of Sderot, a frequent target.

Earlier, an Israeli air raid killed five Hamas militants in southern Gaza.

US Secretary of State Condoleezza Rice said that the Palestinian rocket attacks "need to stop".

"We are all sorry about the death of the Israeli university student" [in Sderot], she said, after meeting Israeli Prime Minister Ehud Olmert in Tokyo.

She added that  "I am concerned about the humanitarian conditions there and innocent people in Gaza who are being hurt."

Ms Rice will visit the Middle East next week for several days of talks with Mr Olmert and Palestinian Authority President Mahmoud Abbas.