Israeli warplanes raided the Gaza Strip early Wednesday after a rocket was fired at southern Israel, a military spokesman said.

"The air force targeted a site used for terrorist activities in the south of the Gaza Strip which was hit," he said in a statement.

The raid came in response to the firing of a Qassam rocket from the Strip at Israeli territory late Tuesday, the spokesman added.

Low-level unrest has rumbled on in and around Gaza for the past 10 days but has not deteriorated into all-out fighting as it did on October 29-30 when tit-for-tat violence left 12 Palestinian militants and an Israeli civilian dead.

Militant groups say they are observing an Egyptian-brokered truce agreement but have reserved the right to reply to any Israeli fire, while Israel has said it will target any militants poised to fire rockets across the border.