HOLY CITY OF KARBALA, Iraq: Husseini mourners from across Iraq and the world thronged the shrine city of Karbala on Saturday for the commemoration of Arbaeen amid tight security.

Officials said some 15 million pilgrims will have passed through Karbala by the end of the commemorations, braving the threat of deadly violence.

"I have been walking for 12 days," said Adil Salim, a devotee from Iraq's southern port city of Basra. "Despite the threats and the exhaustion, we insist on taking part in these commemorations."

"We will never stop, no matter what the terrorists do."

Sad songs blared from loudspeakers throughout the city and black flags fluttered alongside pictures of Hussein and his half-brother Imam Abbas, both of whom are buried in the city.

Karbala provincial governor Amal al-Din al-Har said he expected that some 15 million pilgrims will have visited the shrine city in the two weeks running to Arbaeen's climax on Saturday.

Included in that figure, he said, were around 200,000 devotees from outside the country.

"All services are going smoothly," he told AFP, but noted that the province's electricity and transportation networks were overwhelmed by the sheer number of pilgrims.

Some 35,000 police officers and soldiers were handling security around the city, 110 kilometres (70 miles) south of Baghdad, and eponymous province as pilgrims carried out their traditional walk to Karbala.

Iraq's security forces have also deployed 500 policewomen to assist in checkpoint searches, as well as sonar detectors and sniffer dogs, according to Lieutenant General Othman al-Ghanimi, who commands forces in five provinces across central Iraq, of which Karbala is one.

He said they have so far arrested 60 insurgents they alleged were planning attacks during the pilgrimage, and defused 14 roadside bombs.