A Bangladeshi court on Wednesday dropped an investigation into Tahmid Hasib Khan (pictured), a 22-year-old Canadian university student who investigators had suspected of playing a role in an Islamist attack on a Dhaka cafe this July that killed 22 people, mostly foreign hostages.

Khan's family had said the University of Toronto student was a customer when five Islamist gunmen stormed cafe in the capital's diplomatic district on July 1. He had arrived in Dhaka the day before the attack while on holiday from university.

Prosecutor Abdullah Abu said that investigators had found no link between Khan and the gunmen, nearly three months after he and a British citizen with Bangladeshi roots, Hasnat Karim, were arrested.

No word was heard from either Khan or Karim after commandos raided the cafe, killing all five attackers. Police only admitted the two were arrested weeks after being detained on August 4.

Abu said Karim remained in custody although he had not been formally charged. The prosecutor said Khan was still charged with failing to cooperate with authorities. If convicted, Khan could receive a fine and up to a month in jail.

Bangladeshi police arrested to the two men at the cafe because of their "behavior and actions" during the 12-hour hostage crisis and subsequent raid.

The "Islamic State" claimed responsibility for the attack, but the Bangladesh government has pinned the blame on domestic Islamist groups. Police have killed at least 14 suspected militants, including a Bangladeshi-Canadian, in counter-terror raids related to the cafe attack.

Prime Minister Sheikh Hasina's government has embarked on a major crackdown on Islamist militants, who have carried out a number of attacks in recent years. The extent of the clampdown has sparked concern over the rule of law and raised questions whether she is using the Islamist terror threat to also go after the opposition.

cw/msh (AFP, AP, dpa)