DHAKA (AFP) - Bangladesh on Monday (April 25) rejected the Islamic State in Iraq and Syria's (ISIS') assertion it was behind the murder of a liberal professor and said "local militants" were responsible.

Professor Rezaul Karim Siddique was killed on Saturday by attackers wielding machetes, the latest in a series of murders of secular bloggers and liberal activists that has left the country reeling.

ISIS claimed responsibility for the attack through its news agency, saying the 58-year-old professor who wrote poetry and fiction had been murdered for "calling to atheism".

"Local militants are committing the murders using name of the IS," said Home Minister Asaduzzaman Khan in response, referring to the group by the moniker Islamic State.

He also rejected claims of worsening law and order in the mainly Sunni Muslim country, which has suffered a recent spate of murders of minorities and foreigners as well as of bloggers and activists.

"Murders are happening everywhere in the world," Mr Khan told reporters.

"The law and order situation in Bangladesh is better than many developed countries," he added, calling the murders "isolated incidents".

ISIS has in recent months claimed responsibility for the killing of Christians, Hindu priests and members of the minority Sufi, Ahmadi and Shiite faiths in Bangladesh.

The local branch of Al-Qaeda has also claimed the murders of secular bloggers and activists, including the killing this month of a 26-year-old atheist law student who had mocked Islam on his Facebook page.

Bangladesh police, however, said they suspect banned local Islamist outfits, the Jamayetul Mujahideen Bangladesh and the Ansarullah Bangla Team, of being behind the killings.

"We have already identified some suspects involved in previous killings and incidences of attacks," Mr Khan told reporters.

On Sunday, the police arrested a student from Rajshahi University where Siddique taught, although the hunt was still on for other suspects.

Police said the unidentified student of public administration was a member of Islami Chhatra Shibir, the student wing of Bangladesh's largest Islamist opposition party Jamaat-e-Islami.

A long-running political crisis in Bangladesh, which is officially secular, has radicalised opponents of the government and analysts say Islamist extremists pose a growing danger.