A senior Bangladeshi woman journalist, known for her investigative reporting, was arrested on charges of violating a colonial-era official secrecy law, the police said on Tuesday, triggering protests by the rights groups and her colleagues.

Rozina Islam, a senior reporter of Bangla daily Prothom Alo, the largest daily newspaper based on circulation, was on Monday detained for over five hours by the Health Ministry officials for allegedly clicking a picture of a document with her cell phone without permission. She was later arrested by the police.

The ministry filed a case against her at around midnight under the 1923 Official Secrets Act while she spent her night under the police custody, the police said.

She was produced before a court here with a petition seeking her to be remanded in custody for five days, which the judge rejected and sent her to jail to await the routine legal procedures.

The judge said he would entertain the prosecution charge and the defence statements including her bail petition on Thursday.

A prosecution lawyer told reporters that "whether the allegation is true or false, a case has been filed” which needed a procedure to be disposed of.

Rozina, who earned the reputation of being an investigative journalist, has in recent months published several reports exposing the health ministry’s alleged malpractices during the COVID-19 pandemic, drawing public attention.

She also published several reports involving the health sector which included alleged graft in procurement at the health ministry, corruption in doctors' recruitment and how urgent medical equipment for coronavirus treatment were left at Dhaka airport for months.

"The incident is unfortunate,” Health Minister Zahid Maleque told TV channels without elaborating further, even as reporters boycotted a routine health ministry press conference protesting her arrest.

He also rejected allegations that Rozina's reports on the health sector earned her the wraths of health ministry officials, saying the actions were not led by any "vengeance".

Health Ministry’s Public Relations Officer Maidul Islam Prodhan claimed that Rozina was also taking away some documents when the senior ministry officials challenged her and later called the woman police.

The Prothom Alo newspaper said that she had gone to the ministry for her professional duties, alleging that she was detained under duress for a long five hours and was physically and mentally harassed.

Bangladeshi journalist groups and the Committee to Protect Journalists (CPJ) demanded her release and expressed concerns about the case filed under a draconian colonial-era law that carries ridiculously harsh penalties.

"Bangladesh police and authorities should recognise that Rozina Islam is a journalist whose work is a public service and should immediately drop the case against her and allow her to go free,” the CPJ said in a statement.

Dhaka Union of Journalists (DUJ) in a statement warned tough actions unless steps were taken for Rozina's unconditional release. It expressed regret that she was accused under a "black law" for her reporting when the government declared a "zero tolerance" policy against corruption.

"The journalists are nobody's enemy...Don't push them away, which eventually will benefit the looters," the statement said.

It also called for a protest on Wednesday in the capital over the issue as journalists at different Bangladesh cities staged street demonstrations.

Bangladesh's National Press Club president Farisa Yasmin and general secretary Elias Khan met Home Minister Asaduzzamman Khan Kamal and demanded a proper investigation into the issue and proper facilities for the arrested journalist in jail.