Thousands of miles from Gaza, medical student Samar Alghoul is supposed to be living her dream in Cuba, where she and hundreds of other Palestinians have been given the opportunity to study for free.

But, like the Palestinian diaspora all around the world, she is ridden with anxiety watching the decimation of her home from afar.

The 21-year-old lives in a dorm with six other students at the University of Havana, but often dreams of returning to her family's side, even if it means running towards war.

Hezbollah chief Hassan Nasrallah on Wednesday warned "no place" in Israel would be spared in case of full-blown war against the Lebanese group, and threatened Cyprus if it opened its airports to Israel.

"The enemy knows well that we have prepared ourselves for the worst... and that no place... will be spared our rockets," Nasrallah said in a televised address.

Israel must expect "us on land, by sea and by air", he said.

Brussels has refused to host a Nations League match between Israel and Belgium on September 6 because it could spark demonstrations, city authorities said on Wednesday.

They said holding such a match while the war in Gaza was continuing "will undoubtedly provoke large demonstrations and counter-demonstrations, compromising the safety of spectators, players, Brussels residents and also the police".

An escalating cross-border tit-for-tat between Israel and Lebanon's Hezbollah raised fears Wednesday of a full-blown war, but experts are divided on the prospect of a wider conflict.

The United States was working behind the scenes to ease tensions, a day after Israel's top diplomat warned the Iran-backed Hezbollah that it would be destroyed in the event of a "total war" and the Israeli army said its operational plans for an offensive in Lebanon had been signed off.

- Is conflict around the corner? -

Iranian-Swedish academic Ahmad Reza Jalali, who has been on death row in Iran for eight years, criticised Sweden's prime minister after being excluded from a prisoner swap, in an audio recording obtained by AFP on Wednesday.

Two Swedes were released by Tehran on Saturday in exchange for Hamid Noury, a 63-year-old former Iranian prisons official who was handed a life sentence in Sweden in 2022 for his role in mass killings in Iranian jails in 1988.

Friends and family searched for missing hajj pilgrims on Wednesday as the death toll at the annual rituals, which were carried out in scorching heat, surged past 900.

Relatives scoured hospitals and pleaded online for news, fearing the worst after temperatures hit 51.8 degrees Celsius (125 Fahrenheit) in Mecca, Islam's holiest city, on Monday.

About 1.8 million people from all over the world, many old and infirm, took part in the days-long, mostly outdoor pilgrimage, which this year fell during the oven-like Saudi summer.

Hezbollah on Wednesday said none of Israel would be spared in a war, after Israel said it had approved plans for a Lebanon offensive, stoking fears of the Gaza conflict spreading.

Hezbollah chief Hassan Nasrallah said "no place" in Israel would "be spared our rockets", in a televised address broadcast amid spiralling tensions across the Israel-Lebanon border.

Diplomats on Tuesday said at least 550 pilgrims died during the hajj, underscoring the gruelling nature of the pilgrimage which again unfolded in scorching temperatures this year.

At least 323 of those who died were Egyptians, most of them succumbing to heat-related illnesses, two Arab diplomats coordinating their countries' responses told AFP.

The six candidates vying to succeed ultraconservative president Ebrahim Raisi, who died in a helicopter crash, focused on revitalising Iran's sanctions-hit economy in their first debate ahead of next week's election.

The contenders -- five conservatives and a sole reformer -- faced off in a four-hour live debate, vowing to address the financial challenges affecting the country's 85 million people.

Originally slated for 2025, the election was moved forward after Raisi's death on May 19 in a helicopter crash in northern Iran.

US envoy Amos Hochstein on Tuesday called for the "urgent" de-escalation of cross-border exchanges of fire between Lebanon's Hezbollah and Israeli forces raging since the start of the Gaza war.

"The conflict... between Israel and Hezbollah has gone on for long enough," the presidential envoy said on a visit to Beirut.

"It's in everyone's interest to resolve it quickly and diplomatically -- that is both achievable and it is urgent."