(CNN) Bangladeshis vote Sunday on whether to give Prime Minister Sheikh Hasina a record third consecutive term in an election marred by allegations of human rights abuses by her government.

The military has been deployed across the country to try to prevent the violence seen during recent polls, which were tarnished by a low turnout and boycotted by the largest opposition group and its allies.

The Bangladesh Awami League, led by 71-year-old Hasina, has been in power since 2009 and won the last election in January 2014 with a resounding majority amid a boycott. But Hasina has since been accused of authoritarianism and harassment of the media and opposition figures, even as she presides over strong economic growth.

Prime Minister Sheikh Hasina seen arriving at a Commonwealth Heads of Government Meeting (CHOGM) at Buckingham Palace on April 19, 2018 in London, England.

Concerns over transparency

Human rights groups and opposition figures have warned that the December 30 election could be rigged despite promises of transparency from the authorities.

Salil Tripathi, a London-based journalist and author of "The Colonel Who Would Not Repent: The Bangladesh War and Its Unquiet Legacy," said the government has delayed visas for election observer groups such as the Asian Network for Free Elections (Anfrel) despite its promises of openness.

"The question is whether there will be observers on the ground in time to see what's going on," Tripathi told CNN. "You want elections that are free and fair, and Bangladesh is missing this as an opportunity. If you don't allow the observers to come, how will you prove this?"

In a report last week, Human Rights Watch said a "repressive political environment in Bangladesh is undermining the credibility of the process."

"Authoritarian measures, including widespread surveillance and a crackdown on free speech, have contributed to a widely described climate of fear," the report said, adding that police had failed to act impartially and ignored attacks on opposition figures.

Brad Adams, HRW's Asia director, said "the police and election commission should not appear to be acting like extensions of the ruling party."

"The violence during the campaign that has mainly targeted the opposition bears out their misgivings about unfair treatment," he added.

Much of the campaign violence seen in 2014 targeted the opposition Bangladesh National Party (BNP) and the opposition coalition Jatiya Oikya Front (National United Front).

Supporters of the Bangladesh Awami League shout slogans while taking part in a rally ahead of December 30 general election vote, in Dhaka on December 27, 2018.

Free speech clampdown

Opposition figures aren't the only ones feeling the pressure. Media and press freedom groups have complained of harassment and threats ahead of Sunday's election.

In October, the government approved a controversial new digital security law which rights groups fear could further erode press freedoms and silence dissenting voices online.

Amnesty International said it imposed "dangerous restrictions on freedom of expression" and pointed to its potential for use against opposition voices.

The Dhaka-based Odhikar group has highlighted a worrying spate of what it called "enforced disappearances" of opposition leaders, students and activists.

In September alone, the rights group claims 30 people were picked up by law enforcement agencies without explanation -- a sharp jump from a total of 28 in the first eight months of the year.

One of those detained in 2018 was prominent photojournalist Shahidul Alam, who was jailed for several months after an interview with Al Jazeera in which he accused the government of clinging on to power by "brute force."

A joint statement by 25 human rights organizations, including the Committee to Protect Journalists and Amnesty International, had called for Alam's "immediate and unconditional release" and slammed the allegations against him as "a blatant violation of his right to freedom of expression."

Bangladeshi photographer and activist Shahidul Alam reacts as he is released from Dhaka Central Jail, Keraniganj, near Dhaka, on November 20, 2018.

Weak opposition

Hasina is widely expected to cruise to a third term, with her biggest rival, BNP chief and former prime minister Khaleda Zia, 73, currently in prison and banned from running for election over corruption charges.

BNP supporters claim the charges against Zia are politically motivated.

"I'd be surprised if Hasina doesn't win. The opposition has a lot of problems in terms of pitching candidates and intimidation. She has the advantage of incumbency," Tripathi said.

But regardless of the outcome, he said the focus should be on the rights of Bangladeshis to free and fair polls: "The voters and the candidates need to feel reassured."