More than 5,000 people in Bangladesh have been detained over the past few days in a countrywide security operation to combat increasing attacks on religious minorities and secular activists, the police said Sunday.

Police spokesman Kamrul Ahsan said that since the crackdown began on Thursday, the police had arrested 5,324 people, including 85 suspected Islamist radicals, the Associated Press (AP) reported. The majority of those arrested have petty criminal records. More arrests are expected this week.

At least 18 people, including atheist bloggers, foreign aid workers and religious minorities, have been killed in extremist attacks over the past two years, according to the AP. In separate incidents last week, two Hindus were fatally attacked in the Muslim-majority nation.

The government’s response to this wave of extremism has been mass arrests, made under broad public order legislation. However, a report released by the Brussels-based nonprofit International Crisis Group said: “Heavy-handed measures are denting the government’s legitimacy and, by provoking violent counter-responses, benefiting violent party wings and extremist groups alike.”

It also mentioned that such arrests “without due process and transparency, is fueling alienation that [terrorist] groups can further exploit.” However, the government has dismissed such concerns, the Wall Street Journal reported.

Almost all the attacks have been claimed by transnational Islamist extremist groups, including the Islamic State group and al Qaeda affiliates. The killing Friday of the Hindu monastery worker in northern Bangladesh was also claimed by ISIS.

Dhaka has repeatedly denied the existence of such militant groups in the country. It prefers to lay the blame on domestic groups backed by the opposition, while the latter has denied involvement, hence continuing the volley of blame.

The South Asian country’s parliament has been without an effective opposition since 2014, when opposition parties boycotted national elections. They accused Prime Minister Sheikh Hasina’s government of trying to unfairly sway the vote.