The 58 sites were not registered with the information ministry, official said. (Representational)

Bangladesh's telecoms regulator shut down dozens of online news portals for several hours on Monday, citing security reasons, as officials scrutinise hundreds of sites before a parliamentary election this month.

The move comes as Prime Minister Sheikh Hasina's government is already facing criticism for introducing laws that many journalists fear are aimed at curbing press freedom.

The Bangladesh Telecommunication Regulatory Commission (BTRC) asked International Internet Gateway (IIG) operators to block 58 news sites, BTRC spokesman Zakir Hossain Khan said, without elaborating on the security concerns. The portals were inaccessible for at least 12 hours.

"When an issue is raised to us by the commission which is related to law and order of the country, we are bound to comply," IIG President Sarwar Alam Shikder said.

The 58 sites were found to be not registered with the information ministry and therefore their content was being examined, said Abdul Malek, an official at the ministry.

"It is the responsibility of this ministry to bring all news portals under a system so that they can run smoothly," he said, adding that hundreds of websites were under scrutiny.

While Hasina's government has won widespread global praise for letting in hundreds of thousands of Rohingya refugees who fled persecution in Myanmar, its critics have decried her increasingly authoritarian rule, the government's handling of student protests this year and its crackdown on free speech.

The election is being held on December 30.