DHAKA (Reuters) - A pizza chef killed during a militant attack on a cafe where he worked in Bangladesh’s capital city last week was probably in league with the assailants, police said on Wednesday.

Saiful Islam Chowkidar carried no arms but was seen “moving and running” with the five gunmen during the 12-hour stand-off, Monirul Islam, the chief of counter-terrorism police, said.

On Friday, at least five Bangladeshi men had stormed the Holey Artisan Bakery, a cafe popular with foreigners, businessmen and diplomats and killed 20 customers, including Italians, Japanese, Indians and Americans.

On Tuesday, police said Chowkidar was shot dead by mistake but Islam revised that, saying his death was “not accidental”, although police were unsure how he died and the role he played.

“At one point they (militants) tried to escape. They came out running and started firing, the chef was with them,” Islam told reporters. “He is a suspect member of this group.”

Two other suspects being treated in hospital were also employees of the cafe, police said. One worked as a delivery man and the other in the kitchen.

“Before the final operations, their movement was suspicious,” Islam said.

The attack was one of the deadliest ever in Bangladesh, where the Islamic State and al Qaeda have made competing claims for a series of killings of liberals and members of religious minorities in the past year. The government has dismissed those claims and insists that the violence is homegrown.

The gunmen were mostly from well-to-do families and police gave their names as: Nibras Islam, 20; Rohan Imtiaz, 20; Meer Saameh Mubasheer, 19; Khairul Islam, 22; Shafiqul Islam, 26.

Their attack marked a major escalation in violence aimed at forcing strict Islamic rule onto predominantly Muslim Bangladesh’s 160 million people.

Foreign security experts say the scale and sophistication of the attack pointed to some level of guidance from international militant groups.

But the police believe Jamaat-ul-Mujahideen Bangladesh (JMB), an outlawed domestic group that has pledged allegiance to Islamic State, was to blame.

“We have confirmed these attacks were by JMB,” Islam said.

Policemen sneak a look inside the Holey Artisan Bakery and the O'Kitchen Restaurant as others inspect the site after gunmen attacked, in Dhaka, Bangladesh. REUTERS/Adnan Abidi

Meanwhile, Islamic State warned that attacks would continue until Islamic law was established worldwide, saying in a video that the Dhaka assault was just a hint of what is to come.

“What you witnessed in Bangladesh ... was a glimpse. This will repeat, repeat and repeat until you lose and we win and the sharia is established throughout the world,” said a man identified as Bangladeshi fighter Abu Issa al-Bengali, in the video monitored by SITE intelligence site.

The video began with pictures of recent attacks in Paris, Brussels and Orlando in the United States that the Middle East-based militants have claimed.

Bengali said Bangladesh must know that it was now part of a bigger battlefield to establish the cross-border “caliphate” the group proclaimed in 2014.

Police said they were stepping up security in response to the video threat.