Bangladesh has arrested a suspected Islamist extremist who supplied weapons and explosives for a 2016 siege that killed 22 hostages, a top police official said Sunday.

The Rapid Action Battalion escort arrested suspected militant Mamunur Rashid (C) in Dhaka on January 20, 2019. (Photo: VCG)

Eighteen foreigners were among those shot and hacked to death in the 10-hour standoff at the Holey Artisan Bakery, an upmarket cafe in Dhaka, before military commandos stormed the building and freed some two dozen other people.

Mamunur Rashid was a key "decision-maker" in Jamayetul Mujahideen Bangladesh, a banned homegrown Islamist militant outfit blamed for the attack. 

The 30-year-old was arrested while traveling on a bus outside the capital Dhaka, said Mufti Mahmud Khan, a spokesperson for the elite Rapid Action Battalion. 

Rashid "supplied money, arms, ammunition and explosives for the attack," Khan told reporters. 

"He hid in a neighboring country and tried to reorganize the group. They were also planning to rescue their accomplices from custody."

A former computer operator and Islamic seminary student, Rashid also provided logistical support to Islamists involved in several deadly attacks on religious minorities in the ­country's north, Khan said.

A court in Dhaka last month put eight militants on trial over the cafe attack.

Khan said Rashid was one of the two men charged in absentia, while the other six were already in custody.