Huge crowds swarmed the streets of Bangladesh's capital Wednesday to demand Prime Minister Sheikh Hasina's resignation and fresh elections, with public anger mounting over rising food and fuel costs.

The Bangladesh Nationalist Party (BNP) and other opposition allies staged rallies in Dhaka and nine other cities -- the latest of several demonstrations in recent months that have occasionally been quelled by police violence.

"The time to cling to power by force is over," senior BNP leader Mirza Abbas said at a sit-in outside party headquarters in the capital. "Let a neutral government hold an election."

Police estimated up to 50,000 people were present in the crowd addressed by Abbas, who was released from prison on Monday a month after a sweeping crackdown on opposition activists.

But BNP officials said hundreds of thousands had turned up in Dhaka alone, with thousands of others joining sister rallies around the country.

Bangladesh is one of the fastest-growing economies in Asia, but rising global food and fuel costs linked to the war in Ukraine forced Hasina's government last year to impose lengthy power cuts and expand food handouts to the poor.

The Bangladeshi taka has depreciated by up to 25 percent, driving up the cost of food imports and making life harder for the country's poorest citizens.

The ruling Awami League held a much smaller counter-protest in Dhaka to support Hasina, who has rejected calls for her departure.

"Extremists are gathering in one place to topple us from power," she told supporters at a small gathering on Tuesday.

"Don't think that the party will fall down if it is shaken. Things are not that easy."

Western governments and the UN have expressed concerns over the political climate in Bangladesh, where Hasina's party dominates the legislature and runs it virtually as a rubber stamp.

In December 2021, Washington levelled sanctions against top security officers over their roles in hundreds of enforced disappearances and thousands of extrajudicial killings.

Hasina's government denies it was behind any enforced disappearance of opposition supporters and leaders, and says many criminals were killed during gunfights with officers.