NEW DELHI: In the three months since a band of youths tortured and killed 20 hostages in a Dhaka restaurant, Bangladeshi intelligence officials say they're rooting out radicals and restoring security to the streets. Their evidence? Police raids that have killed about 40 suspected Islamist militants; hundreds of suspects detained in police dragnets; and new information on how the attack was financed by local sympathizers.

There have also been no reported extremist attacks since shortly after the restaurant killings.

The police raids followed an unprecedented crackdown over the summer, during which authorities arrested more than 14,000 people before July — most for petty crimes including theft and small-time drug smuggling. The arrests have continued, netting 1,200 suspected militants, some of whom are giving up useful information under questioning, intelligence officials say. But they refuse to say how many in total have been detained in recent months.

When asked to quantify the anti-militant operation's success, Monirul Islam, the head of the police counter-terrorism and transnational crime units, said it was "60 to 70 percent."

"Still, we need to apprehend some command-level people. We are looking for them," he said.

Some analysts, however, say the pursuit of low-level operatives has done little to ensure national security or to reveal who was really behind the July 1 hostage-taking — the country's deadliest attack in years of sustained militant violence targeting writers, religious minorities and others deemed enemies of Islam.

"Given the depth of the crisis, the country has still a long way to go," said Abdur Rashid, a security expert and a retired major general. "Our investigators are very good at traditional investigation, but this is a difficult case — finding the real people who planned, backed and helped execute the plan ... We do not know actually what is going on. We are depending on the police version only."

Bangladesh's secular government has been under intense international pressure to crack down on Islamist militancy since the July attack, during which five Bangladeshi youths seized a popular eatery in Dhaka's diplomatic quarter and terrorized dozens of hostages overnight, eventually killing 20 of them, including 17 foreigners.

Just days later, bombs hurled at an Islamic festival killed one and triggered public protests in Dhaka's streets, with Bangladeshis demanding the government do more to establish better security.

In both cases, the government dismissed claims of responsibility by the Islamic State group, and instead blamed domestic militants backed by the opposition. Prime Minister Sheikh Hasina has said IS has no presence in the country, and is capitalizing on the bloodshed for propaganda purposes.

The government continued to deny any IS role even after an August raid killed three suspected militants, including a Canadian man of Bangladeshi origin identified on an Islamic State website as the extremist Sunni group's representative in Bangladesh. Authorities deny the man, Tamim Chowdhury, had any IS link, and instead say he was a leader within the banned militant group Jumatul Mujahedeen Bangladesh, or JMB.

Officials denied any IS role again this week, even as police said one of the sources of financing for the restaurant attack was a pediatrician whom they say fled with his family to Syria to join the IS group. Two other men were also accused helping to provide a total of about $100,000 for the attack: a retired army major who donated his pension and savings, and another man who donated proceeds from an apartment sale in Dhaka. Both were killed in police raids.

Some wonder if the government's insistence that the IS plays no part in the violence is short-sighted, and may prevent it from understanding how global jihadist networks may be operating in Bangladesh.

"What matters isn't necessarily what the government says, but what it is investigating, and I believe they are investigating these connections," said foreign policy analyst Veena Sikri, a former Indian ambassador to Bangladesh.

She said investigations have shown at least a tenuous connection between IS and some recent attacks in Bangladesh, with IS working through expatriate Bangladeshis as the extremist group tries to establish itself in the country — as they are attempting to do in India.

So far, the government has pointed the finger at a one of its old foes — the JMB. Unlike earlier days when most of the group's members came from Islamic schools or were returning from the Middle East, the government said JMB is now recruiting tech-savvy and well-educated youths from privileged backgrounds. That profile matches at least three of the July 1 attackers, who had studied at the country's top universities.

"We have been able to weaken their network," Islam, the police official, told the Associated Press. "Many of the top organizers have been killed, and others have been identified."

There have been no reported attacks by Islamist extremists in Bangladesh since the festival bombing in the first week of July. In the preceding two years there had been dozens of isolated attacks targeting and often killing foreigners, atheist bloggers, writers, liberal publishers and members of religious minority communities.

Some critics, including Amnesty International and Human Rights Watch, have warned that authorities' blunt approach is exposing Bangladesh to complaints of rights abuses, as hundreds of people — including a Briton and a Canadian — have been detained for months without charge.

Authorities released the Canadian student earlier this month, but British-Bangladeshi national Hasnat Karim, one of the hostages during the July 1 attack, has been in custody for more than 100 days. Authorities have offered no information about his whereabouts or the investigation against him.

A spokesman for the country's elite anti-crime force Rapid Action Battalion said the raids since July have nevertheless succeeded in breaking down networks of radical groups, especially the JMB. Some of those raids were staged on isolated river shoals and small islands, where makeshift militant training camps had been set up.

"This is a continuous process," spokesman Mufti Mahmud Khan said. "We will not stop."

Intelligence officials said the more than 1,200 suspected militants detained in the police dragnet include 643 men and women allegedly involved with JMB.

They said they are also searching for another 80 suspects they described as well-trained and "dangerous" — information that they said came directly from questioning detained suspects. Interrogations have also given officials a list of "killers" who took part in attacks on atheist bloggers, writers, religious minorities and others in recent years.

After one raid earlier this month, the home minister implored the country's youth to turn away from radicalism.

"We don't want to kill people," Asaduzzaman Khan said. "You who have chosen a wrong path. Return to normal life. We will help you to maintain a normal life. Our doors are open."