DHAKA (AFP) - A Bangladesh opposition activist and a businessman were remanded in police custody on Tuesday (Oct 5) for questioning about the murder of a Japanese farmer, an attack claimed by the Islamisc State in Iraq and Syria (ISIS).

A court ordered the pair detained for 10 days over the shooting of Mr Hoshi Kunio on Saturday in the northern city of Rangpur, the second foreigner killed in less than a week.

"A magistrate court in Rangpur remanded the two into custody for ten days for intensive interrogation over the murder," investigating officer Mamunur Rashid told AFP.

Rashid said police picked up the pair just hours after the murder, although they have not been named as suspects.

One of them, Rashedun Nabi Biplob, is a former leader of the main opposition Bangladesh Nationalist Party's (BNP) student wing and an active member, the party said.

Prime Minister Sheikh Hasina has blamed the BNP and its Islamist ally, Jamaat-e-Islami, for instigating attacks on the foreigners, a claim rejected by the parties.

Humayun Kabir Hira, the second man remanded, became friends with Mr Kunio, who leased farmland from Mr Hira's brother-in-law in the town of Kaunia, according to police and another newspaper.

Three men riding on a motorbike shot the 66-year-old Mr Kunio dead after stopping his rickshaw on a dirt road.

The militant group later claimed responsibility for the killing, according to the SITE Intelligence Group, a US monitoring organisation, although experts are dubious.

ISIS also said it was behind the killing of Italian aid worker Cesare Tavella on Sept 28 as he was jogging in Dhaka's diplomatic quarter. No one has been arrested over that murder.

Experts say Islamist militants pose a growing danger in Muslim-majority Bangladesh, warning that a long-running political crisis has radicalised opponents of the government.

The assassination of four atheist bloggers since the turn of the year undermines the government's efforts to play down the threat posed by hardliners, experts say.