The Bangladesh Nationalist Party (BNP), whose leaders are either in jail or in exile, stayed away from the polls after Hasina refused its demand that she resign and let a neutral authority run the general election.

The U.S. State Department said the elections were not free and fair. The British government's foreign office also condemned what it called "acts of intimidation and violence".

Hasina, 76, is the daughter of Sheikh Mujibur Rahman, founding father of the South Asian nation who was killed in an army coup in 1975 along with most members of the family. Hasina first became prime minister in 1996. This will be her fifth term overall.

President Mohammed Shahabuddin administered the oath of office at a ceremony at the presidential palace attended by political leaders, high civil and military officials, diplomats and other dignitaries.

"I am, Sheikh Hasina, taking oath...that I will discharge my duties faithfully as the prime minister of the government as per the law," Hasina said to applause.

Hasina's 36-member cabinet was also sworn into office during the ceremony broadcast live on television.

The BNP, which has boycotted two of the last three elections, says Hasina's party is trying to legitimise a sham vote.

Hasina said she did not need to prove the credibility of the election to anyone. "What is important is if the people of Bangladesh will accept this election."

Hasina has been credited with turning around the economy, though critics have also accused her of human rights violations and suppressing dissent.

But the economy has slowed sharply since the Russian invasion of Ukraine pushed up prices of fuel and food imports, forcing Bangladesh to turn last year to the International Monetary Fund for a $4.7 billion bailout. Inflation was 9.5% in November.

Sharply rising living costs sparked violent protests in the months leading up to the election, as Hasina's government struggled to pay for energy imports due to shrinking dollar reserves and a weakening local currency.

While analysts say economic reforms are urgently needed they also stress that before Hasina's government can proceed, the ruling party and the opposition need to reach some form of an understanding to end political unrest.

Both Hasina and her rivals have accused their opponents of trying to create chaos and violence to thwart political peace and jeopardize democracy that has not yet taken firm root in the country of 170 million people.

(Reporting by Ruma Paul; Editing by Nick Macfie)

By Ruma Paul