One of Bangladesh's key newspapers critical of the government said Sunday its website had been blocked, as the country votes in a general election boycotted by the opposition.

Sajid Hoque, news editor at the Daily Manab Zamin, said the paper had been "flooded with calls and messages" from readers who said "that they cannot access our website".

The newspaper's printed edition was still available on the streets.

Prime Minister Sheikh Hasina is guaranteed to win a fifth term after a boycott led by an opposition party she has branded a "terrorist organisation".

Hasina has presided over breakneck economic growth in a country once beset by grinding poverty, but her government has been accused of rampant human rights abuses and a ruthless opposition crackdown.

The paper, one of the most popular in the South Asian nation and known for its critical coverage of political affairs, posted on its Facebook page on Saturday that the blockage was not due to "any technical issues" on its site.

"Manab Zamin's website is not accessible from across the country", the paper posted.

AFP could not access the website in Dhaka, and Bangladesh internet monitor Activate Rights reported that the site had been offline since Saturday.

International media watchdog Reporters Without Borders (RSF), which ranks Bangladesh 163rd out of 180 countries in its world press freedom index, warned ahead of the vote of what it dubbed the government's "harmful grip on information".