Pakistan is observing Chehlum of Hazrat Imam Hussain (R.A) and martyrs of Karbala here on October 30 (Sunday).
Processions will be held in different parts of the country amid tight security.
Cellular and internet services have been suspended in many cities.
A ban on pillion riding has also been imposed in Sindh.
In Karachi, the main procession will start from Nishtar Park at 1 PM and pass through MA Jinnah Road to culminate at Imambargah Husainain Iranian in Kharadar.
The procession has started in Lahore and will end at Karbala Gamay Shah.
More than 9,000 security officers have been deployed.
The procession will be monitored using the CCTVs of the Safe City project.
In Rawalpindi, the procession will start from Imambargah Ashiq Hussain. All the routes leading to the Imambargah have been sealed.
Seven thousand policemen have been deployed for security.
Heavy corpses of police and Rangers will be present along the procession, while checkpoints will also be checked with the help of tracked dogs.
Main roads to witness the processions have been sealed by the containers.
Karachi police chief, Additional Inspector General Ghulam Nabi Memon, outlined the security measures taken which includes a heavy deployment of police, suspension of mobile phone services and a ban on pillion riding.
Furthermore, the playing/possessing of audio or video containing provocative speeches and initiating sectarian hatred, has been prohibited.
Like Lahore and Islamabad, thousands of small processions will be held in the cities of Karachi, Rawalpindi, Peshawar and Quetta on the occasion of Chehlum Imam Hussain (R.A), amid strict security measures across the cities.