A statement issued by the US state department said: "In this light, we note with concern credible reports of harassment, intimidation, and violence in the pre-election period that made it difficult for many opposition candidates and their supporters to meet, hold rallies, and campaign freely. We are also concerned that election-day irregularities prevented some people from voting, which undermined faith in the electoral process."

The United States is Bangladesh’s largest foreign investor, largest single-country market for Bangladeshi exports, and home to a large community of Americans of Bangladeshi origin.

"We strongly encourage all parties to refrain from violence and request the Election Commission work constructively with all sides to address claims of irregularities. Bangladesh’s impressive record of economic development and respect for democracy and human rights are mutually reinforcing, and we look forward to continue working with the ruling government and opposition towards advancing these interrelated goals," it said.

General polls in the Muslim majority country was held on Sunday.

Amid reports of sporadic violence, which left 17 people dead, Bangladesh's ruling Awami League returned to power for the third straight time.

Sheikh Hasina, who has been in power since 2009, will become the country's PM for another term.

Awami League and its alliances won 288 of the 300 seats it contested in the polls.

The opposition alliance, Jatiya Oikya Front, won just 7 seats.