Shias all over the world mark the Chehlum or Arbaeen of Hazrat Imam Hussain (RA) 40 days after Ashura.

Chehlum processions kicked off in various cities of Pakistan under tight security, as cellphone services were suspended and traffic diverted from procession routes.

Millions of Shias also thronged to Karbala in Iraq for the culmination of one of the world's largest religious events.

The faithful have for days been streaming through the golden-domed mausoleum of Hazrat Imam Hussain (RA), the Prophet Muhammad's (PBUH) grandson who was killed in 680 AD by the armies of Yazid, despite the threat of militant attacks.

Many in the sea of black-clad devotees swarming the shrine walked days to reach Karbala, sometimes from cities as far afield as Basra, about 500 kilometres away by road.

PAKISTAN

People participate in a Chehlum procession in Islamabad. — AP

A man pets Zuljinah on the Chehlum of Hazrat Imam Hussain(RA). —Reuters

Teary-eyed women mourn at the Chehlum of Hazrat Imam Hussain (RA). — AFP

Children walk among the security vehicles protecting the funeral procession in Islamabad. — AFP

Women look on as the procession passes by. — AFP

A robot conducts a security sweep of the procession area as a child looks on. — AFP

Men beat their chests during the Chehlum rituals. — AFP

Security vehicles parked at the procession site. — AFP

Women cry during the Chehlum procession. — AFP

People touch a horse, symbolising Zuljinah, the horse that carried Hazrat Imam Hussain (RA) during the battle of Karbala, at the procession marking Chehlum. — AFP

People look on as men perform rituals during the Chehlum procession. — AFP

Thousands of devotees take part in the Chehlum procession. — AFP

IRAN

Men perform prayers as part of the Chehlum rituals. — AP

Men beat their chests during the Chehlum mourning. — AP

A man mourns as others look on during the Chehlum rituals. — AP

Men gather to take a procession out to commemorate Chehlum. — AP

IRAQ

Pilgrims gather as they commemorate Chehlum in Karbala, Iraq. — Reuters

Pilgrims mourn as they commemorate Chehlum. — Reuters

Female pilgrims mourn during the Chehlum rituals. — Reuters