An Israeli air strike on the Gaza Strip Saturday killed a key Salafist leader and a fellow activist, Palestinian security sources said.

Jordanian national Sheikh Hisham al-Saedini, 43, also known as Abu Al-Waleed Al-Maqdissi, of the Mujahedeen Shura Council was killed in the attack in the northern town of Jabaliya, the sources said.

Fellow Salafist Islamic activist Fayek Abu Jazar, 42, also died in the raid, the Palestinian security sources added.

A 12-year-old boy was among two other people who were wounded in the attack, according to Palestinian medical officials said.

The two Salafist activists had been riding a motorbike at the time of the air strike, according to the medical sources.

Hisham al-Saedini was head of radical Gaza Salafist group Tawhid wal-Jihad and one of the founders of the Mujahedeen Shura Council, a new Salafist coalition in the Palestinian enclave.

Jordanian Hisham al-Saedini was considered one of the most important Salafist leaders in Gaza.

He was originally held by Hamas following the kidnap and murder of Italian peace activist Vittorio Arrigoni last year but was released in August following Jordanian intervention.

The Salafist groups accuse Hamas of weakness in the face of Israel and of failing to apply Islamic law.

The attack was one of several on the coastal strip over the course of the day.

An Israeli military spokesman said the attack targeted members of the Mujahedeen Shura Council, a Salafist group, who were "responsible for terrorist activities."

Following the fatal strike, the air force also hit a training camp in Gaza City of the Ezzedine al-Qassam Brigades, the armed wing of the Islamist movement Hamas, which controls the strip, Palestinian sources said.

No casualties were reported from that attack.

Earlier on Saturday, the air force hit three targets in Gaza hours after a rocket fired from the territory exploded near a house in southern Israel, sources on both sides said.

"Aircraft targeted a terror activity site in the northern Gaza Strip, and two terror activity sites in the central Gaza Strip. Direct hits were confirmed," a statement from the Israeli military said.

"The sites were targeted in response to the rocket fire towards southern Israel."

Palestinian security officials said there were no casualties from the strikes, one of which hit an unmanned training camp of the Ezzedine al-Qassam Brigades, the armed wing of the ruling Hamas movement, south of Gaza City.

They said the other two hit open ground near the Nusseirat and Al-Bureij refugee camps in central Gaza, possibly used as rocket launch sites.

On Friday night, Gaza militants fired a Grad rocket that exploded in the yard of a residential building in the southern Israeli town of Netivot.

One person was taken for medical treatment suffering from shock, and the building was damaged by the rocket.

The Mujahedeen Shura Council issued a statement saying it had fired the rocket on Netivot.

There has been a flurry of tit-for-tat violence on the Gaza-Israel border in recent days.

On Thursday, Israeli warplanes raided a training camp of the Ezzedine al-Qassam Brigades, several hours after Gaza militants fired two rockets into southern Israel.

On Wednesday the Israeli air force struck targets in northern Gaza, also without causing casualties. The strikes came after rocket fire that was also claimed by the Mujahedeen Shura Council.

Earlier in the week, the armed wings of Hamas and Islamic Jihad launched a barrage of fire at southern Israel a day after warplanes raided the southern city of Rafah, targeting two men the military said were global jihad activists.

The two were critically wounded and one later died. Another eight people were wounded, among them five children.

Monday's rocket fire by Hamas and Islamic Jihad militants marked a rare show of force given that the two groups normally observe a de facto truce on rocket fire on Israel.

The last time Hamas militants fired on Israel was during a flareup in June when militant groups fired more than 150 rockets, wounding five people, and Israel hit back with air strikes that killed 15 Palestinians.

According to the Israeli military, more than 480 rockets or mortar rounds have been fired at southern Israel from Gaza this year.