An Israeli air strike killed the Palestinian leader of an al Qaida-affiliated group in the Gaza Strip on Saturday, Hamas and medical sources said.

Gaza Medics said a second militant was also killed in the strike. The after-dark attack targeted the two men who were riding a motorcycle in the northern town of Jabaliya.

The interior ministry of Hamas, the Islamist group that controls Gaza, said one of the men killed was Hisham Saedni, also known as Abu Al-Waleed Al-Maqdissi, believed to head the Jihadist Salafi group Tawhid and Jihad (One God and Holy War).

Sources from Tawhid and Jihad could not be reached to confirm that Saedni was killed.

The group, rival to Hamas, has an Islamist ideology shared by al Qaida and sources have said that Saedni joined al Qaida in Iraq at the beginning of the U.S.-led invasion in 2003.

In March 2011 Hamas detained Saedni for 17 months and had freed him in August.

Last year members identifying themselves with Tawhid and Jihad kidnapped and killed a pro-Palestinian Italian activist, Vittorio Arrigoni, in an apparent attempt to secure the release of Saedni.

An Israeli military spokesman could not confirm Saedni was the target of the air strike. A written military statement said the two men targeted were "terror operatives of the Shora Council of the Mujahideen, a Gaza-based Global Jihad affiliate."

The same group had claimed responsibility for a rocket that was fired into Israel on Friday and landed near a house in the Israeli town of Netivot, causing damage but no casualties.

In response, a few hours later, the Israeli military launched three air strikes against what it said were "terror activity sites." There were no casualties reported in those attacks.

A source in the IDF said that one of the militants was involved in the attack that took place on the Israel-Egypt border in June, in which a worker hired by the Defense Ministry was killed.

Saturday's strike was the fourth such attack over the weekend.

A statement issued by the IDF Spokesperson unit said: "The IDF will not tolerate any attempt to harm the citizens of the state of Israel or IDF soldiers and will continue to act forcefully and decisively against anyone who commits terror acts against the State of Israel."

Israel says it holds Hamas responsible for any attacks launched from Gaza, which has been under the group's control since 2007. An Israeli military spokesman said that about 40 rockets were fired from Gaza into Israel in October.

Hamas rejects permanent peace with Israel and the two sides fought a three-week war in December-January 2008-2009. The border is tense, with frequent clashes.

A number of Jihadist Salafi groups have surfaced in Gaza in recent years. Unlike Hamas, they endorse an ideology of global Jihad and some accuse Hamas of failing to implement Islamic laws in the coastal enclave.

On Monday, the IDF struck a number of sites in Gaza in response to a barrage of rocket and mortar fire, for which the armed wing of Hamas and Islamic Jihad claimed responsibility.    

The rocket fire, which continued throughout the morning hours on Monday, was in response to the IDF targeting two Gaza militants - killing one of them and injuring 11 civilians - the previous night.