Palestinian Islamic Jihad, an armed group based in Gaza, was blamed by the Israel Defence Forces on Tuesday night after hundreds of people were reported killed by a strike at Ahli Arab Hospital in Gaza City.

The Israeli military said the blast was caused by a rocket fired by the group that malfunctioned after launching. Gazan health authorities said the blast had been caused by an Israeli airstrike.

What is Islamic Jihad?

The second-largest armed group in Gaza, Islamic Jihad has often been eclipsed by the larger Hamas organisation, which has controlled and governed Gaza since 2007.

Islamic Jihad was founded in the 1980s in the Gaza Strip to fight the Israeli occupation and maintain a presence in Gaza and the West Bank.

Iran supports both groups with weapons. Israel and the US consider both to be terrorist organisations.

In May, the Israeli military said it had targeted and killed three Islamic Jihad leaders that it said were responsible for rocket attacks against Israel and other attacks against Israeli citizens in the West Bank.

In the past, rockets fired by Palestinian armed groups, including Islamic Jihad, have occasionally malfunctioned and hit civilian neighbourhoods.

What links extremists?

Hamas and Islamic Jihad are often aligned against Israel. They are the most important members of the joint operations room, which coordinates most military activity among the various armed groups in the tiny coastal enclave of Gaza.

But at times, it is a tense relationship, especially when Hamas has exerted pressure on Islamic Jihad to stop attacks or retaliation against Israel.

Islamic Jihad often acts independently of Hamas and is focused primarily on military confrontations.

On some occasions, Hamas has stayed on the sidelines as Islamic Jihad has clashed with Israel.

In other cases, Hamas has joined Islamic Jihad in battling the Israeli military.

West Bank teens shot

Israeli forces shot dead two Palestinian teenagers near Ramallah in the West Bank on Wednesday during widespread protests against Israel’s bombing of the Gaza Strip, Palestinian officials said.