Israeli warplanes destroyed the Beirut office of senior Hamas official Mohammed Nazzal during an attack this afternoon.
A Hamas official said Mr Nazzal escaped injury. It is not clear if Nazzal was in his office at the time or if there were any casualties.
Israeli aircraft earlier targeted the Palestinian Economy Ministry and a house in Gaza on Saturday, part of an offensive to free a captured soldier and prevent the functioning of the Hamas-led government.
Doctors said one person was killed in the attack on the house, which was in a densely populated neighbourhood, and eight people were wounded, including a baby and a child.
Israel said the house was targeted because it was being used as a place to manufacture and store weapons, including rockets.
"The explosion was very large from all the explosives inside," an army spokeswoman said. "We knew militants from Hamas were staying inside and were working to make a rocket."
Palestinian medics said it appeared most of the casaulties involved people who were outside the house at the time.
The strike came hours after the Economy Ministry was hit.
Undeterred by its widening offensive inside Lebanon, Israeli aircraft also bombed a bridge in central Gaza, witnesses said. Palestinian officials said there no casualties in the bridge or ministry attacks, which were confirmed by the Israeli army.
Gunmen from the militant Hamas movement were among factions that seized Corporal Gilad Shalit on June 25. Hamas, which won control of the Palestinian government after winning elections in January, is sworn to Israel's destruction