Two Palestinians were killed Monday in a second Israeli air strike on the northern Gaza town of Beit Hanun, raising the overall toll to four dead, Palestinian medics said.

"Two people were killed in a Zionist air strike on a street in Beit Hanun," an official at Kamal Edwan hospital told AFP after the second such strike on the town in seven hours.

At least three other people were wounded in the attack, he said, without saying how badly.

Ezzedine al-Qassam Brigades, the military wing of the Islamist Hamas rulers of Gaza, identified one of the dead men as one of its activists, 23-year-old Jihad Abu Shbab, a statement said.

A medical source named the other dead man as Mohammed al-Zaanin, 25, and said he was not affiliated with any armed faction.

The earlier strike targeted a motorcycle just east of Beit Hanun, killing two Islamic Jihad activists, medics and witnesses said.

The Israeli military confirmed the strike, saying it had targeted "a terrorist squad attempting to fire a rocket at Israel." Troops identified "a direct hit," the statement said.

The two air strikes came just hours after after gunmen mounted a deadly ambush along Israel's southern border with Egypt, killing an Israeli civilian construction worker.

But an Israeli military source earlier insisted the initial air strike was "in no way related to today's incident along the Israel-Egypt border."

During Monday, police said a rocket was fired into the Hof Ashkelon region of southern Israel, which lies just north of the Gaza Strip, causing no injuries or damage.

Overnight, the air force staged two raids over Gaza, hitting a weapons manufacturing site in the south and another "terror activity site" in the centre of the coastal strip.

The raids came several hours after militants fired eight mortar rounds at troops on the border.