UN peacekeepers in Lebanon on Friday warned of "very serious risks" for their Blue Helmets after explosions wounded two mission members near the Israeli border, the second such incident in two days.

The Israeli military said its forces on Friday fired at a threat near a UN peacekeeping mission position.

Israel and Hezbollah have been clashing in south Lebanon since last week when Israel announced "targeted" incursions into Lebanon against the Lebanese militant group, which is backed by Iran.

Swedish activist Greta Thunberg attended a climate change and pro-Palestinian rally in Milan on Friday, days after her criticism of Israel sparked a row over protests in Germany.

More than 1,000 people, many of them teenagers, joined a peaceful march in the northern Italian city organised by Fridays For Future, the climate change movement Thunberg helped found.

Wearing a keffiyeh, a traditional scarf symbolising the Palestinian struggle against Israel, Thunberg walked near the front of the procession as other protesters waved flags, held banners and danced to music.

The displacement of hundreds of thousands of people in Lebanon is "devastating", a UN migration official has said, warning international support was falling short of the needs, amid intense Israeli bombing.

After a year of cross-border fire between Israel and Hezbollah, which launched attacks on Israel in support of its ally Hamas in Gaza, Israel last month escalated attacks on what it says are Hezbollah targets in Lebanon's south, east and south Beirut.

Lebanese Christian Joseph Jarjour was hoping for a peaceful retirement at home in south Lebanon, but has instead found himself caught in the crossfire of the Israel-Hezbollah war.

"We're trapped," said the 68-year-old retired teacher in the southern village of Rmeish, around two kilometres (one mile) from the Israeli border.

After almost a year of cross-border fire, Israel began conducting a wave of strikes targeting Hezbollah strongholds and sent ground troops across the border late last month.

Fearing becoming targets as the Middle East conflict spreads, wealthy Gulf states are shoring up ties with Iran and giving assurances they won't facilitate attacks by Israel, analysts said.

Traditionally Western allies, the resource-rich monarchies have grown closer to Iran after a long period of tension with their giant neighbour across the Gulf.

As Israel says it is preparing a response to Iran's 200-missile barrage on October 1, a rapid series of diplomatic exchanges shows the Gulf is keen to stress its neutrality in the conflict, experts said.

Israel observed Yom Kippur, the holiest day in the Jewish calendar, on Saturday amid a firestorm of international criticism over its military offensive in Lebanon and its soldiers firing on peacekeepers.

As the holy day got under way Friday from sundown, Israel faced diplomatic backlash over what it acknowledged was a "hit" earlier in the day on a United Nations peacekeeping position in Lebanon.

Two Sri Lankan peacekeepers were hurt in the second such incident in two days, the UNIFIL mission said Friday.

Loud bangs sounded, thick columns of smoke rose and ambulance sirens rang throughout the night as deadly Israeli strikes hit residential areas of central Beirut on Thursday evening.

The Israeli attacks hit two central Beirut locations, killing 22 people and injuring over 100, Lebanon's health ministry said.

They were the deadliest such attacks to target central Beirut since Israel intensified its bombardment campaign on the country two weeks ago.

Civilians fled heavy bombings in northern Gaza on Thursday as Israeli troops advanced on Jabalia refugee camp, leaving many trapped in the line of fire.

"The bombardment has not stopped. Every minute there are shells, rockets and fire on the buildings and everything that moves", Areej Nasr, 35, told AFP after fleeing from Jabalia camp to Gaza City Thursday.

She said those wounded in strikes could not be rescued.

"No ambulance has arrived, and no one is assisting the wounded. There are dozens lying on the ground," Nasr said.

Exhausted but relieved, hundreds of Turkish citizens and their families docked in southern Turkey late Thursday after being evacuated from war-torn Lebanon on two naval ships sent by Ankara.

"The situation is very bad back in Beirut. My kids were very scared. We are the lucky ones," Esra Gongu, a mother in her thirties told AFP on disembarking from the TCG Bayraktar which docked at 9:00 pm (1800 GMT) after a 13-hour journey.

A second boat, the TCG Sancaktar, was to land at midnight, officials said.

The Committee to Protect Journalists accused Israel of a lack of accountability Thursday over the killing of a Reuters journalist and the wounding of six other reporters including two AFP staff a year after the incident.

The CPJ said the absence of serious investigations into what independent probes conclude was the firing by Israel of tank shells at a group of seven journalists in southern Lebanon gave Israel's forces license to do it again.