A Spanish man who was documenting his journey on foot from Madrid to Doha for the 2022 Fifa World Cup has not been heard from since crossing into Iran three weeks ago, his family have said.

An experienced trekker, former paratrooper and soccer fan, 41-year-old Santiago Sanchez was last seen in Iraq after hiking through 15 countries and sharing his journey on Instagram over the last nine months. But his posts stopped suddenly on October 1, the day he entered Iran from the country’s northwestern border.

Mr Sanchez’s family says his daily WhatsApp updates stopped on that day as well.

Mr Sanchez’s parents have reported him as missing to Spain’s national police and the Foreign Ministry.

But Spanish authorities say they have no information about his whereabouts, adding that the Spanish ambassador to Tehran was handling the matter.

“We are deeply worried, we can’t stop crying, my husband and I,” his mother, Celia Cogedor, said.

Mr Sanchez’s reported disappearance in Iran — his last stop before reaching Qatar for the World Cup — comes as protesters rise up across the Islamic Republic in the largest anti-government movement in over a decade.

The demonstrations erupted on September 16 over the death of Mahsa Amini, a 22-year-old woman taken into custody by Iran’s morality police for allegedly not adhering to the country’s strict Islamic dress code.

Tehran has violently cracked down and blamed foreign enemies and Kurdish groups in Iraq for fomenting the unrest, without offering evidence.

The Iranian Intelligence Ministry said authorities had arrested nine foreigners, mostly Europeans, over their alleged links to the protests last month.

Mr Sanchez arrived in Iraqi Kurdistan in late September, after trekking thousands of kilometres carrying a small suitcase in a wheeled cart. He said he wanted to learn how others lived by living among them before reaching Qatar, the first World Cup host country in the Arab world, in time for Spain’s first match on November 23.

“The idea of the journey is to motivate and inspire other people to show that they can go very far with very little,” he told the Associated Press from Sulaymaniyah, a Kurdish city in northeastern Iraq. “You can go a long way walking.”

The day before he disappeared, Mr Sanchez had breakfast with a guide in Sulaymaniyah who said he tried to warn Mr Sanchez about the dangerous political situation in Iran.

Protests in Iran’s Kurdish region after Amini’s death kindled the nationwide unrest still roiling Iran. In response, Iranian forces have unleashed drone and artillery attacks targeting Kurdish separatists in northern Iraq.

But Mr Sanchez was undeterred and confident, the guide said.

Mr Sanchez, the guide added, planned to meet an Iranian family in the Kurdish town of Marivan — a scene of recent antigovernment protests.

The Spanish Foreign Ministry said it had registered Mr Sanchez’s border crossing into Iran and was not ruling out any possibilities.