DHAKA, Bangladesh — Bangladesh’s governing party won handily in Sunday’s parliamentary elections, clinching a third consecutive term for Prime Minister Sheikh Hasina even as widespread reports of irregularities, voter intimidation and violence cast the voting into question.

Mrs. Hasina’s party, the Awami League, and its allies officially won 288 of the 298 parliamentary seats that have been called by the Election Commission, with a total of 300 seats up for grabs.

But the opposition swiftly rejected the results, accusing the governing party of tampering with votes and calling for a fresh election. Mrs. Hasina, 71, is the first leader in Bangladesh’s history to win three consecutive terms, but she has increasingly been accused of autocratic behavior.

The opposition leader Kamal Hossain denounced the “farcical election” on Sunday night as the results streamed in. The Election Commission said it was looking into reports of irregularities.