SEHWAN SHARIF: Wailing Sufi devotees thronged the blood-stained shrine of Sufi Saint Lal Shahbaz Qalanadar in Sehwan Sharif on Friday, shouting at police a day after a suicide bomber killed over 80 people in an attack claimed by a regional branch of Islamic State aka Daesh.

Followers of the revered Sufi saint however have remained undeterred and vowed to hold the dhamaal ritual as usual after tonights evening prayers.

The bombing of the famed Lal Shahbaz Qalandar shrine was Pakistan's deadliest attack in two years.

An offshoot of the Middle East-based Islamic State said it was responsible for the bombing, the second major attack on a Sufi shrine in three months.

The white marble floor at Lal Shahbaz Qalandar was still marked by blood on Friday, and a pile of abandoned shoes and slippers was heaped in the courtyard, many of them belonging to victims.

Outside, protesters shouted slogans at police, who they said had failed to protect the shrine.

"I wish I could have been here and died in the blast last night," a devastated Ali Hussain told Reuters, sitting on the floor of the shrine.

He said that local Sufis had asked for better security after a separate bombing this week had killed 15 people in Lahore, but added: "No one bothered to secure this place".

Anwer Ali, 25, rushed to the shrine after he heard the explosion, and described seeing dead bodies and chaos as people fled the scene.

"There were threats to the shrine. The Taliban had warned that they will attack here, but authorities didn't take it seriously," Ali said.

A wave of bombings over five days has hit all four of Pakistan's provinces and two major cities, killing over 100 people and shaking a nascent sense that the worst of the country's militant violence may be in the past.

Most of the other attacks have been claimed by factions of the Pakistani Taliban, which is waging its own fight against the Pakistani government but whose ranks have also cooperated with and sometimes defected to Islamic State.