The Israeli military said Thursday that militants in the Gaza Strip have test-fired rockets into the Mediterranean Sea, in an apparent attempt to show off their capabilities amid increased tensions in the wake of this week's deadly synagogue attack.

Four rockets were fired in the past 24 hours, the military said, without elaborating on the test or type of rockets fired. There was no immediate confirmation from Palestinian officials in Gaza.

Israel and Gaza's Hamas rulers fought a 50-day war over the summer that claimed more than 2,100 Palestinian and 70 Israeli lives.

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At the time, Israel said it launched the operation to halt Hamas' rocket attacks from Gaza — rockets that now have the ability to reach Tel Aviv, Jerusalem and other Israeli cities. And though the rocket fire continued throughout the war, it was largely neutralized by Israel's "Iron Dome" aerial defence system.

Tensions in the region have spiked in recent weeks, largely over a disputed holy site in Jerusalem sacred to both Muslims and Jews. Palestinian attackers have killed 11 people in five separate incidents, including Tuesday's storming of a Jerusalem synagogue that killed four worshippers and an Israeli policeman. At least five Palestinians involved in the attacks were killed.

The violence has prompted anti-Arab demonstrations by Israeli right-wingers. On Wednesday, Mayor Itamar Shimoni of the southern Israeli city of Ashkelon suspended Israeli Arab labourers from work. They were renovating bomb shelters at local day-care centres.

The move drew criticism on Thursday, including from Prime Minister Benjamin Netanyahu who said "there is no place for discrimination against Israeli Arabs." Economy Minister Naftali Bennett, who anchors the far right wing of Netanyahu's coalition, insisted that "99 per cent of Israeli Arabs are completely loyal" to Israel.

Arab Israelis make up about 20 per cent of Israel's population of 8 million people. Tensions over the Jerusalem holy site have infiltrated into their community as well, prompting angry demonstrations and in one case, the fatal police shooting of an Arab Israeli man who approached a police car wielding a knife.