Image copyright Reuters Image caption The attack is thought to have targeted police

At least nine people have been killed in an explosion outside a major Sufi Muslim shrine in the Pakistani city of Lahore, officials said.

Five police officers are reportedly among the dead. A police van was the prime target, authorities said.

Police have described the blast as a suicide attack.

It has been claimed by the Hizbul Ahrar, a splinter group of the Pakistani Taliban.

The explosion occurred at 0844am local time (0344 GMT) near the Data Darbar Sufi shrine, one of the oldest Sufi shrines in South Asia.

The bloodshed comes as Pakistani Muslims mark the Islamic holy month of Ramadan.

A security operation is still under way in the area, with a heavy police presence at the blast site.

Footage from the scene shows a badly damaged police vehicle surrounded by debris near a security checkpoint at the shrine.

Prime Minister Imran Khan denounced the attack.

Skip Twitter post by @ImranKhanPTI Strongly condemn the terror blast outside Data Darbar this morning. Have asked Punjab govt to provide all assistance to the injured & families of victims. — Imran Khan (@ImranKhanPTI) May 8, 2019 Report

The Data Darbar shrine

Image copyright AFP Image caption The shrine was packed with devotees when it was attacked in 2010

Located near the Bhati Gate inside the ancient Walled City of Lahore, Data Darbar is one of the largest Sufi shrines in South Asia.

Built in the 11th Century, it is where Sufi saint Abul Hassan Ali Hajveri - also known as Data Ganj Baksh - was laid to rest.

It is considered to be one of the most sacred sites in Lahore.

It is visited by hundreds of thousands of people each year from both Sunni and Shia traditions of Islam.

In 2010, dozens died in two suicide blasts at Data Darbar.

Police said, although there was no specific threat against the shrine, worshippers should remain vigilant during the month of Ramadan.

Sufism is a form of Islamic mysticism that exists across the Islamic world, and includes both Sunnis and Shias.

Its followers in Pakistan have been attacked by militants in the past.

Some extremists view Sufis as heretics for not adhering to their fundamentalist form of Islam.

Pakistan has cracked down on a number of extremist groups - including Pakistani Taliban factions - in recent years.

But while security has improved the country still grapples with attacks by militants who are opposed to the government.

In 2016, at least 72 people were killed in Lahore in a bombing targeting Christians on Easter Sunday.