Polls in Bangladesh opened on Sunday for a general election that is being boycotted by the main opposition party, with the country's leader Sheikh Hasina — the world's longest serving female prime minister — set to win her fourth consecutive term. Bangladesh, a country of some 170 million people, is the first in South Asia this year to head to the polls. Around 120 million people are registered to vote. The country has seen political unrest leading up to Sunday's general election. Polling booths were set ablaze on the eve of the vote, with four people, including two children, killed in a train fire, reported Reuters. The country is also beset by economic problems, requiring a nearly $5 billion loan from the International Monetary Fund last year. Prime Minister Sheikh Hasina, in power since 2009, cast her vote in the capital Dhaka. A win would mark a fifth overall victory for her Awami League-led alliance. "Our country is a sovereign and independent country – maybe we're small but we have a big population," she told reporters at a press conference in Dhaka. "We have established people's democratic rights and also the right to a better life. That is our main aim." "I want to make sure that democracy should continue in this country," she continued, adding that "without democracy, you cannot make any development." Overseas watchdogs have expressed concerns the country was heading towards a one-party system. The main opposition Bangladesh Nationalist Party is boycotting the elections after Hasina denied calls to resign and let a neutral caretaker government run the election. — CNN