DHAKA - Bangladesh police said Tuesday they have identified three people as financial backers of a group blamed for a deadly attack on a cafe, including a doctor who joined Islamic State militants in Syria.

Gunmen raided the cafe in a smart Dhaka neighbourhood on July 1 and killed 20 mostly foreign hostages, the deadliest in a series of such attacks which have blighted Bangladesh in the last three years.

The IS group claimed responsibility for the carnage but the government blamed a new faction of the Jamayetul Mujahideen Bangladesh (JMB). It launched a major crackdown against the local militant group that left 40 members dead.

Dhaka police counter-terrorism chief Monirul Islam said two suspected militants, including a retired army major, have been identified as funding the JMB. They were killed in police raids last month.

Islam said a doctor also funded the group, donating eight million taka ($10,000).

The ex-army officer gave his retirement benefits and the other militant handed over the proceeds of an apartment sale.

“The doctor has gone to Syria to join the Islamic State. The other two were killed during anti-militant raids last month,” a Dhaka police spokesman also told AFP.

Local media have reported that the paediatrician, who had worked at a state-run children’s hospital, and his family went missing months before the cafe attack.

Police have named former JMB leader Tamim Chowdhury as the mastermind of the attack. Chowdhury, a Canadian citizen of Bangladesh origin, was shot dead in a gunfight in August.

The JMB, long dormant after their top leaders were executed in March 2007, has recently regrouped with young and university-educated extremists taking the helm.

Bangladesh has been reeling from a wave of recent attacks with targets including foreigners, rights activists and members of religious minorities.

Critics say Prime Minister Sheikh Hasina’s administration is in denial about the nature of the threat posed by Islamist extremists. They accuse her of trying to exploit the attacks to demonise her domestic opponents.

In August US Secretary of State John Kerry said during a visit to Dhaka that evidence existed to link the extremists behind the attacks in Bangladesh to IS.