KARACHI: Police in Karachi has arrested four suspected militants they said were planning a wave of sectarian attacks in the city, following a bloody three days in which around 40 people were killed.

Mohammad Aslam Khan, the head of the police anti-extremism cell in southern Sindh province, said the four were members of Lashkar-i-Jhangvi (LeJ), a banned Sunni militant group blamed for many deadly attacks on Shias.

Khan said the men were planning strikes during Muharram, when Shias hold public processions, and police had seized at least 25 kilograms of explosives, along with grenades, automatic rifles and pistols.

Of the 40 or so killed in the city of 18 million people over the past three days, 24 were in sectarian or political violence, Khan said. More than half of the victims were Shias.

“The objective of this wave of target killings was to spread sectarian strife in the city as a prelude to Muharram,” Khan told AFP.

Lashkar-i-Jhangvi is regarded as the most extreme Sunni terror group in Pakistan and is accused of killing hundreds of Shias since its emergence in the early 1990s.

It developed close ties to al Qaeda and the Taliban, which ruled in Afghanistan from 1996 until the 2001 US-led invasion.

Pakistan formally banned the group in 2001 and there have been numerous crackdowns with arrests and killings of known Jhangvi operatives over the last 20 years.

Chief of LeJ, Malik Ishaq, is implicated in dozens of cases, mostly murder. He was released on bail in July last year after serving a jail term of nearly 14 years.

Since his release he had been frequently put under house arrest as his sermons raised sectarian tensions, officials said.

A spokesman for the government paramilitary Rangers told AFP on Tuesday that troops arrested 23 other suspects across the city, including an alleged “notorious” target killer Shamim ur Rehman, in a bid to stop targeted killing.