Most of the victims in a deadly blaze that engulfed a block housing immigrant workers were from India, Kuwait's foreign minister said on Thursday, raising the death toll to 50.

Three Filipinos were among the dead, Philippines officials said, after the fire sent black smoke billowing through the six-storey building south of Kuwait City.

Most of oil-rich Kuwait's four million-plus population is made up of foreigners, many of them from South and Southeast Asia working in construction and service industries.

Frenchman Louis Arnaud returned to Paris on Thursday after his release from a more than 20-month prison ordeal in Iran, but a dozen Europeans are still detained in the Islamic republic.

Activists and some Western governments, including France, accuse Iran of exercising a strategy of taking foreign nationals as hostages to force concessions from the West.

Israeli helicopters struck Rafah on Thursday, residents said, with militants reporting street battles in the southern Gazan city as US President Joe Biden called Hamas the "biggest hang-up" to another truce.

Tensions were also soaring on Israel's northern border, with more attacks by Hamas ally Hezbollah targeting military positions and a civilian reported killed in an Israeli strike in Lebanon.

A massive fire at an oil refinery in Iraqi Kurdistan raged for about 20 hours and injured at least 14 firefighters who on Thursday finally brought the blaze under control.

The fire broke out in a major crude oil tank on Wednesday night before spreading to a second refinery on a road southwest of Arbil, capital of the autonomous northern region of Kurdistan, the civil defence agency said.

Thick plumes of black smoke and balls of orange flame rose into the sky above the facility, an AFP photographer reported.

French citizen Louis Arnaud returned to Paris Thursday after being held in Iran since September 2022 and sentenced last year to five years in jail on national security charges.

Emerging from a small plane at Le Bourget airport outside Paris, a visibly tired but smiling Arnaud shook hands with Foreign Minister Stephane Sejourne before embracing his parents, according to images aired on television.

Arnaud linked arms with his relatives as they entered a private room at the airport out of view of the cameras.

Ukrainian President Volodymyr Zelensky, on an unannounced visit to Saudi Arabia on Wednesday, said he discussed preparations for a peace summit this weekend with Crown Prince Mohammed bin Salman.

Zelensky landed in the Red Sea city of Jeddah for his latest trip to the Gulf kingdom, which has sought to stay neutral in Ukraine's war with Russia.

In a post on social media, he said he held an "energetic meeting" with the Saudi de facto ruler.

US Secretary of State Antony Blinken vowed Wednesday to work to seal a Gaza ceasefire agreement, saying not all Hamas demands were acceptable but voicing hope gaps could be closed.

Consulting with key mediator Qatar on the Hamas response to the plan outlined by US President Joe Biden, Blinken said the Palestinian group could have given a "clear and simple yes" but voiced guarded hope for moving forward.

"We believe that some of the requested changes are workable and some are not," Blinken told reporters in Doha.

It is Islam's holiest pilgrimage, but the hajj to Mecca in Saudi Arabia, which begins on Wednesday, has in recent decades been plagued by deadly disasters, from stampedes to militant attacks.

Last year, 1,301 pilgrims, most of them unregistered and lacking access to air-conditioned tents and buses, died as temperatures soared to 51.8 degrees Celsius.

Here are some incidents that have marred the centuries-old pilgrimage:

- Stampedes -

A fire in Kuwait killed 49 people when it ripped through a building housing nearly 200 foreign workers on Wednesday, the government said.

The blaze, which broke out in the six-storey building south of Kuwait City at around dawn, also left dozens injured, the health ministry said.

Flames engulfed the lower floors as black smoke poured out of the upper-storey windows, unverified images posted on social media showed.

The interior ministry revised the death toll up to 49, from 35 issued earlier, after forensic teams scoured the charred building.

The annual hajj pilgrimage, one of the five pillars of Islam, will start on Wednesday with well over one million Muslims from around the world expected to take part.

All Muslims are expected to complete the hajj to Mecca -- from which non-Muslims are strictly banned -- at least once in their lives if they have the means to do so.

Believers converge on the holy city for several days of rituals in which they retrace the Prophet Mohammed's last pilgrimage.

Here is a rundown of the ceremonies at what is usually one of the largest religious gatherings in the world: