Clashes have rocked the main commercial district in the Bangladeshi capital, Dhaka, as police battled with opposition protesters demanding a halt to the country's war crimes trials.

At least a dozen people were injured by rubber bullets during the clashes, a medical official told the AFP news agency on Wednesday.

Police and witnesses said the clashes - in an area that houses top banks, the main stock market and insurers - began after the supporters of Bangladesh's largest Islamic party, Jamaat-e-Islami, tried to hold marches.

They torched a bus and attacked vehicles with police reacting by firing rubber bullets, witnesses said. Television footage showed police in armoured vehicles and wielding fire-arms chasing protesters.

"At least 100 people have been arrested," sub-inspector Rafiqul Islam said.

Jamaat activists also resorted to violence in the port city of Chittagong, Dhaka based The Daily Star said.

"It's an unfair process, we have demanded that there should be an international tribunal under the auspices of the United Nations to hold fair trial, so that everybody could accept the judgment," Abu Baker Molla, Jamaat-e-Islami spokesman, told Al Jazeera from London. 

Ongoing protests

Wednesday's violence comes a day after more than a dozen people were injured, including the editor of a leading daily, in similar clashes between the police and protesters.

Demonstrations over the trials have left seven people dead since last month.

The protesters have been demanding a halt to the trials of Jamaat leaders for crimes including genocide and rape, which they are alleged to have committed during the country's 1971 war of independence against Pakistan.

A senior Jamaat leader Abdul Quader Mollah was sentenced to life imprisonment last week for mass murder, while former leader Abul Kalam Azad was sentenced to death in absentia, last month.

Eight other Jamaat officials, including its leader and deputy leader, are also being tried along with two officials of the main opposition Bangladesh Nationalist Party (BNP).

Tens of thousands of protesters rallied across Bangladesh last week, demanding the execution of Mollah.

The opposition has called the trials politically motivated, part of a wider vendetta against their leaders.

The government says that three million people were killed during the war, many by pro-Pakistani militias whose members allegedly included Jamaat officials. Independent estimates put the figure much lower.

Source: Al Jazeera and agencies