The United States is concerned about reports of intimidation and political violence during protests in Bangladesh over the weekend against Prime Minister Sheikh Hasina, State Department spokesperson Matthew Miller said on Monday.

Police on Saturday fired rubber bullets and tear gas at stone-throwing opposition party supporters, who called for Hasina to step down and for elections due in January to be held under a neutral caretaker government.

"We encourage the government of Bangladesh to investigate reports of violence thoroughly, transparently and impartially, and to hold the perpetrators of violence to account," Miller said.

Miller urged Bangladesh to create a safe environment for people to peacefully assemble and for all parties to "refrain from violence, harassment and intimidation," noting the upcoming elections.

"Free and fair elections depend on the commitment of everyone - voters, political parties, youth wings, and police, and cannot take place in an environment of political violence," he said.

In May, Washington said it would restrict visas for Bangladeshis who undermine the democratic process at home, after accusations of vote-rigging and suppressing the opposition marred elections in 2014 and 2018. Hasina's government has denied the charges.

Hasina, who has maintained tight control since coming to power in 2009, has been accused of authoritarianism, human rights violations, cracking down on free speech and suppressing dissent while jailing her critics.

Earlier in July, the United States called on the Bangladesh government to conduct thorough and impartial investigations into any reports of violence after a parliamentary candidate was attacked during the Dhaka-17 by-election.

"I would say that this type of political violence has no place in democratic elections," said Matthew Miller, a US state department spokesperson during a press conference in Washington.

The Miller made the comment after Ashraful Alom, popularly known as Hero Alom, an independent candidate in the Dhaka-17 by-election, came under attack while leaving a polling centre in Banani.

"We encourage the Government of Bangladesh to investigate any reports of violence thoroughly, transparently, and impartially, and to hold the perpetrators of violence to account."

However, Washington still expects a fair and free general election to take place in Bangladesh and will continue to monitor the situation closely, according to Miller.