Turkey struck several targets in Syria on Tuesday after President Recep Tayyip Erdogan issued new threats to launch a ground operation "soon" against Kurdish fighters despite calls for de-escalation from Washington and Moscow.

Ankara launched a series of air strikes in Operation Claw-Sword on Sunday -- hitting dozens of Kurdish targets across Iraq and Syria -- and announcing that its military was once again "on top of the terrorists".

The air raids followed a bombing in Istanbul on Sunday that killed six people and wounded 81.

The Kurdish-led Syrian Democratic Forces Tuesday urged the United States and Russia to work for deescalation after Turkey launched deadly cross-border raids against its fighters and threatened a ground offensive.

Turkey launched a series of air raids on Saturday and Sunday against Kurdish armed groups in northern Syria and northern Iraq, following last week's deadly bomb attack in Istanbul which Ankara blamed on those groups.

Iran said Tuesday it had begun producing uranium enriched to 60 percent at its Fordo plant, an underground facility that reopened three years ago amid the breakdown of its nuclear deal with major powers.

The International Atomic Energy Agency confirmed the move, which Iran said was part of its response to the UN nuclear watchdog's adoption last week of a censure motion drafted by Western governments accusing it of non-cooperation.

Five people died and 40 were injured when a gas tank exploded and sparked a fire in a student dormitory in northern Iraq, authorities said Tuesday.

The blast hit Monday night when a rooftop gas tank leaked at a building housing the student accommodation and a bakery in the Kurdish city of Dohuk.

"The gas leaked, reaching the students' rooms, and police arrived to evacuate them," Dohuk's governor, Ali Tatar, told AFP. "Unfortunately at that moment, the explosion occurred."

The United Nations' top rights body will hold an urgent meeting this week to consider launching an international investigation into the deadly crackdown on mass protests rocking Iran.

The UN Human Rights Council is due to host a special session on Thursday on "the deteriorating human rights situation", following a request by Germany and Iceland.

The meeting follows two months of protests in Iran sparked by the death of 22-year-old Mahsa Amini, after she was arrested for an alleged breach of the country's strict dress rules for women based on Islamic sharia law.

Lionel Messi will embark on Tuesday on what will surely be his last chance to win the World Cup, with Argentina and holders France both in action in Qatar.

After England thumped Iran 6-2 to showcase their title credentials, day three of one of the most controversial World Cups in history will have four matches.

Messi and his strongly fancied Argentina side are up first when they face Saudi Arabia in Group C, followed by Denmark versus Tunisia in Group D.

Madrid has repatriated two Spanish women who were married to Islamic State group fighters, flying them home from jihadist camps in Syria with 13 children, the government said on Tuesday.

They arrived at Torrejon de Ardoz military airport near Madrid late on Monday, nearly two months after the Spanish government agreed to bring them home.

"The government has just repatriated two women and 13 Spanish minors from Syrian refugee camps," a foreign ministry statement said.

As the World Cup brings some of the best-known names in sports to Qatar, youth football academies in neighbouring Saudi Arabia expect a spike in registrations but urge more investment.

The Gulf kingdom has long been obsessed with football, but interest in playing -- not just watching -- has surged in recent years amid a government push to promote physical activity under Crown Prince Mohammed bin Salman's Vision 2030 reform agenda.

Turkish President Recep Tayyip Erdogan on Monday threatened to launch a ground operation into Syria, following cross-border air strikes on Kurdish positions and deadly fire on Turkey.

"There is no question that this operation be limited to only an aerial operation," Erdogan told reporters on a flight home from Qatar after attending the opening of the World Cup.

"We will make those who disturb us on our territory pay," he added.

The Turkish leader has threatened a new military operation into northern Syria since May.

Qatari media laid into a "weak" performance by the national team on Monday after the hosts' much-heralded World Cup debut ended in a tame 2-0 defeat by Ecuador.

Any buzz from the opening ceremony soon fell flat as Qatar shipped two goals in the first half, with thousands of fans leaving Al Bayt Stadium well before the game had finished.

While Qatar's press praised the opening ceremony, which included US actor Morgan Freeman and a severely disabled Qatari man, they were critical of coach Felix Sanchez's team.