Israeli aircraft carried out three apparent warning strikes in the Gaza Strip early Wednesday, hitting empty fields after a militant rocket earlier struck waste ground in southern Israel, Palestinian security sources told AFP.
They said that the strikes, the first since the end of a deadly eight-day confrontation between Israel and Hamas militants in November, hit in two spots close to Gaza City and one other site further north toward the frontier with Israel. Nobody was injured.
The Israeli military had no immediate information.
On Tuesday Gaza militants fired a rocket into southern Israel after the death in custody of a Palestinian who suffered from cancer, Israeli police said.
"There was a rocket that was fired," police spokesman Micky Rosenfeld told AFP. "It landed in an open area," he said, adding there were no immediate reports of casualties or property damage.
Earlier in the day Palestinian witnesses told AFP militants in Gaza City had fired three mortar rounds on Israel.
The Israeli army initially said one projectile had landed in the Jewish state, without causing any casualties, but later said none had.
A spokeswoman said military systems detected launches within Gaza but that they had fallen short and landed within the strip.
A coalition of Salafist groups later claimed that its militants fired two rockets at Israel on Tuesday afternoon.
The Mujahedeen Shura Council said in a statement received by AFP that its action was "part of our answer to the death of Maisara Abu Hamdiyeh".
Abu Hamdiyeh, a 63-year-old prisoner from the West Bank city of Hebron, had been suffering from throat cancer. His death on Tuesday morning sparked Palestinian anger, with officials blaming Israel for allegedly refusing to release him early on compassionate grounds.
Hamas spokesman Sami Abu Zuhri told AFP the faction was watching the developments with "the greatest concern" and that Israel would "regret its continuing crimes".
It was the third instance of rocket fire since the end of the November fighting, which ended with an Egyptian-brokered truce that has been almost completely respected.
The previous time rocket fire hit Israel was on March 21 during a visit by US President Barack Obama, when two rockets also claimed by the Salafists caused some damage but no injuries.