Israeli fighter jets bombed the Gaza Strip in the early hours of Friday, amid a sharp escalation of violence after militants in Lebanon and Gaza fired a volley of rockets at Israel.

The Israeli military said that it had hit four targets — including two weapons manufacturing sites and two tunnels — belonging to the Hamas group, which controls the blockaded coastal enclave. Militants returned fire, setting off air-raid sirens in southern Israel.

The exchange of fire followed two days of mounting tensions at Jerusalem’s al-Aqsa mosque, after Israeli police forcibly removed Palestinian worshippers from the site on both Tuesday and Wednesday nights.

As anger over the scenes at al-Aqsa mounted in the Arab world, militants in Lebanon fired 34 rockets at Israel on Thursday afternoon. Israeli media said it was the biggest barrage from the country since 2006, when the Hizbollah militant group and Israel fought a 34-day war.

Air defences intercepted 25 rockets but at least five landed in Israel and paramedics said two people had been injured.

A spokesman for Israel’s military said it believed Palestinian militants in Lebanon — affiliated with either Hamas or Islamic Jihad — had fired the rockets. But he added that it also assumed that Hizbollah, which in recent years has developed increasingly close ties to Palestinian groups both inside and outside Lebanon, had been aware of the attack.

Earlier in the day, Palestinian militants in Gaza launched seven surface-to-air rockets, which exploded in flight without causing injuries.

The escalation is a major security challenge for Israel’s hardline government, which took office last year with ultranationalists in security posts pledging a tougher stance against Palestinians. After a security cabinet meeting early on Friday, prime minister Benjamin Netanyahu said Israel’s response “tonight and in the future, will exact a heavy price”.

No one immediately claimed responsibility for the rocket fire from Lebanon. Both Hizbollah, whose Iran-backed paramilitary is the most powerful group in Lebanon, and Palestinian groups in Lebanon are suspected to have been behind previous cross-border incidents.

Hamas leader Ismail Haniyeh, who was in Lebanon on Thursday in what officials told local media was a “personal visit”, met leaders of Palestinian groups in the country. He called on factions to “unite and escalate” their resistance to defend al-Aqsa “by any means necessary”.

Following the Gaza strikes, Al Mayadeen TV, a Lebanese television station close to Iran and Hizbollah, said the militant group had placed its long-range missile units on high alert. Meanwhile, some Israeli cities announced they were opening public bomb shelters.

The rocket salvos followed a second night of tension at al-Aqsa, known to Jews as the Temple Mount, with Israeli police entering the hilltop compound to remove Muslim worshippers who had tried to stay in the mosque overnight.

The Palestinian Red Crescent said six people had been injured at the compound and two hospitalised, one with an injury from a rubber bullet and another suffering blunt trauma. Police said they had responded to youths throwing fireworks and stones.

Shortly before the rocket fire from Lebanon, Hizbollah condemned the treatment of Palestinians at al-Aqsa, calling it “a flagrant violation of believers in Jerusalem”. It said it backed “all moves by Palestinian people and resistance to defend worshippers and deter the Israeli aggression”.

The al-Aqsa compound, which is the third holiest site in Islam and the holiest in Judaism, is one of the most sensitive places in the Israeli-Palestinian conflict. Clashes there have sparked broader conflagrations, including an 11-day war between Israel and militants in Gaza two years ago.

Israel has occupied the West Bank and East Jerusalem, including the Old City, where the al-Aqsa compound is located, since 1967.

Under the so-called status quo agreement, both Muslims and non-Muslims can visit the site, but only Muslims are allowed to pray there. In recent years, however, Jewish groups have also prayed there, stoking anxiety among Muslims that the status quo was being eroded.

Those fears have been exacerbated by the presence of ultranationalists in Israel’s hardline new government, such as Itamar Ben-Gvir, a settler who has long called for Jewish prayer at al-Aqsa. Netanyahu on Thursday said the status quo would not change, and called for calm at the site.

Wednesday night’s unrest was less intense than the previous night, when footage of heavily armed Israeli forces entering the mosque and beating Palestinians with rifle butts and batons sparked outrage in the Arab world, as well as an exchange of fire between militants in Gaza and Israel.

The violence, which erupted as Muslims celebrated the holy month of Ramadan and Jews began the week-long Passover festival, follows a year of heightened Israeli-Palestinian tensions that has raised fears of a broader conflict.

In the past year, Israeli forces have killed more than 250 Palestinians in the West Bank, while Palestinians have killed more than 40 Israelis.