Here are key facts about the election in the South Asian country of almost 170 million people:

* The main opposition Bangladesh Nationalist Party of the ailing former prime minister Khaleda Zia is boycotting the poll after Hasina denied their demand to step down and make way for a caretaker government to run the election.

* Women make up almost half of the nearly 120 million eligible voters, while first-time voters number about 15 million.

* Vying for 300 parliamentary seats are a total of 1,896 candidates, 5.1% of them women, for the highest such share ever.

* Hasina has been credited with turning around the $416-billion economy and its massive garments industry, while also winning international praise for sheltering nearly a million Rohingya Muslims fleeing persecution in neighbouring Myanmar.

* But in recent months, the economy, once among the world's fastest growing, was rocked by violent protests, following a jump in the cost of living, as Bangladesh struggles to pay for costly energy imports amid depleting dollar reserves and a weakening domestic currency.

* The International Monetary Fund (IMF) cleared the first review of Bangladesh's $4.7 billion bailout in December, providing immediate access to about $468.3 million and made $221.5 million available for its climate change agenda.

* Rights groups have also accused the government of targeting opposition leaders and supporters, while Hasina and her Awami League have repeatedly condemned the BNP as troublemakers set on sabotaging the elections.

* Nearly 750,000 police, paramilitary and police auxiliaries will guard the polls on election day. Officials of the army, navy and air force have also been deployed.

* As many as 127 foreign observers will track the election process to assess its fairness, while 59 journalists from abroad have been accredited.

* The top buyer of Bangladeshi garments, the United States, warned in May that it would curb visas to Bangladesh citizens who undermine the democratic election process.

* Voting begins at 8 a.m. (0200 GMT) and ends at 4 p.m. (1000 GMT) on Sunday.

* Counting will start soon after the end of voting, with initial results expected by Jan. 8.

(Compiled by Sudipto Ganguly and Ruma Paul; Editing by Clarence Fernandez)

By Ruma Paul and Sudipto Ganguly