Israeli navy commandos launched a ground operation overnight in the north of the Gaza Strip, the first since the offensive against Hamas began, Israeli public radio said early Sunday.

The brief incursion targeted a rocket launcher site, it said. The armed branch of Hamas confirmed that Israeli commandos had exchanged gunfire with some Palestinian fighters.

A military spokesman later said four Israeli soldiers had been lightly wounded during the operation.

"During the mission a gunfight broke out, started by some terrorists operating at the site, during which four Israeli soldiers were lightly wounded," said the spokesman who declined to give further details on the operation.

The Ezzedine al-Qassam Brigades, the military wing of Hamas, confirmed the exchange of gunfire "between our fighters and soldiers of the Zionist navy which tried to penetrate the zone of Sudanyia" in northwest Gaza.

It was the first ground operation in Gaza by the Israeli military since the start of its offensive on Tuesday.