Police in Bangladesh have arrested 3,245 people in the past 24 hours, as security forces continue their crackdown on those suspected of involvement in the slayings of secular activists and religious minorities.

The total number of suspects arrested since the campaign began on Friday stands at 8,192, police spokesman Kamrul Ahsan said on Monday.

At least 103 of those arrested were tied to the spate of killings targeting religious minorities and secular activists, with about 6,000 on other charges related to firearms, drugs, and other offences, police said.

Over the past week, an elderly Hindu priest, a Hindu monastery worker, and a Christian shopkeeper were hacked to death in attacks for which the Islamic State of Iraq and the Levant (ISIL) group claimed responsibility.

The Muslim wife of a "counter-terrorism" police official was also stabbed and shot dead in a separate attack.

ISIL claims

The attackers have killed more than 30 people in Bangladesh since early last year, with atheist bloggers, liberal academics, gay rights campaigners, foreign aid workers, members of minority Muslim sects and other religious groups among the victims.

ISIL (also known as ISIS) has claimed responsibility for 21 of the attacks since its first claim in September last year and al-Qaeda has claimed most of the rest, according to Site Intelligence Group, a US-based monitoring service.

The government denies that either group has a presence in Bangladesh and says home-grown activists are responsible.

Last month, junior foreign minister Shahriar Alam told Reuters that ISIL was trying to ride a wave of violence by falsely claiming killings and said there was enough evidence implicating domestic groups.

Prime Minister Sheikh Hasina has vowed to track down the killers, blaming the growing violence on political opponents linked to Islamist parties.

The main opposition party, led by former Prime Minister Khaleda Zia, dismisses such accusations and said the mass arrests were a ploy to suppress political opponents.