Bangladesh police on Saturday arrested a politician accused of masterminding the murder of a journalist who had written stories about his family.

Mahmudul Alam Babu was arrested near the Indian border after a nationwide manhunt, the country's elite Rapid Action Battalion (RAB) said in a statement.

The 50-year-old is accused of organizing Wednesday's murder of Golam Rabbani Nadim, who was beaten by a gang of men near his home in Jamalpur district and later died in hospital.

Babu was retaliating for a series of stories on a custody dispute involving a child following his recent divorce, local police chief Sohel Rana told Agence France-Presse (AFP).

"He is the number one accused in the case over the murder of the journalist," Rana said. "A journalist saw him on the spot when Nadim was beaten by a group of men," he added.

Rana said Babu was the general secretary of the local wing of Prime Minister Sheikh Hasina's ruling Awami League.

The party announced Babu's expulsion immediately after he was named a suspect in the killing.

Six other people were also arrested over the murder, Rana said.

Local press club president Shaheen Al Amin told AFP that Babu had been angered by Nadim's "extensive coverage" of his family dispute.

Babu had filed a defamation suit against the reporter but a court quashed the case on Tuesday, Amin said.

"The next day Nadim was attacked by Babu's men and he was hit on his head with a brick. He died due to internal bleeding," he added.

Journalist groups staged protests after the murder to demand the arrest of the culprits.

Reporters Without Borders ranked Bangladesh 163 of 180 countries in its 2023 World Press Freedom Index.

Journalists with Bangladesh's dwindling independent media outlets have been under increasing pressure from the government and Hasina's ruling party.

In March the editor of the country's largest newspaper and a reporter were charged under the controversial Digital Security Act for writing an article on the high cost of food.

Authorities shut down the lone opposition mouthpiece in February, saying it violated press laws.