Rival activists clashed in a northeastern Bangladesh city, leaving at least 20 people injured, as widespread protests to force electoral reforms crippled Bangladesh for a fourth day Wednesday, witnesses said.

The violence occurred between supporters of former Prime Minister Khaleda Zia and Sheikh Hasina in Sylhet city's Chondi Pool area, a witness, Humayun Rashid Chowdhury, told The Associated Press by telephone from the scene.

The clash erupted after Zia's supporters attacked protesters who were blocking the city's main railway station, 192 kilometers (120 miles) northeast of the capital, Dhaka, Chowdhury said.

Zia's supporters set seven motorcycles on fire belonging to the protesters and damaged another 10 parked near the scene, said another witness, Abdul Baten.

The political scene remained tumultuous Wednesday despite warnings from business leaders about damage to the country's economy and efforts by a caretaker government to end the impasse.

Dhaka, the capital city of 10 million people, has remained cut off from the rest of the country since strikes, blockades and demonstrations started on Sunday.

Tens of thousands of demonstrators blocked main roads and rail lines across the country, while there has been practically no trade at any of Bangladesh's sea or land ports.

An alliance of 14 political parties, led by the Awami League, began the indefinite, nationwide strike and blockade in an effort to force the removal of election officials they call biased ahead of January elections.

The alliance has demanded the removal of four top Election Commission officials, accusing them of bias toward the former coalition government led by Khaleda Zia who completed her five-year term as prime minister on Oct. 28. The commissioners deny the allegation and have refused to resign.

A caretaker government headed by President Iajuddin Ahmed is running the country until the elections.

In Dhaka, the protesters burned effigies of Aziz at several demonstrations.

The paralyzing protests disrupted supplies of essential commodities like rice, fish and vegetable to the capital, raising the prices by at least 30 percent, business leaders said Wednesday.

"We fear the prices will jump further if the strike continues," said Abdur Razzaque, who runs a wholesale rice store in Dhaka.

Protesters who returned home during the nightfall were back on the streets Wednesday in Dhaka. The streets were still empty of traffic except tricycle rickshaws that were allowed by the protesters to operate.

Many commuters either used the pedicabs or walked to their work.

Most stores and schools remained closed.

About 15,000 security forces have been deployed in Dhaka to prevent any violence. There were no reports of unrest Wednesday.

On Tuesday about two dozen protesters were hurt when riot police used batons to disperse rival supporters who fought pitched battles on the streets of Chittagong and Mymensingh, AP correspondents at the scenes said.

A delegation of business leaders met President Ahmed on Tuesday to urge him to do something to bring an end to the political impasse, saying the impoverished country was teetering on the brink of collapse.

"Our economy can't afford such an anarchic situation for long," Mir Nasir Hossain, leader of the delegation, told the AP after the meeting.

Shipments in and out of Chittagong, a southeastern port city that handles about 75 percent of Bangladesh's sea cargo, have been hampered since Sunday, port official Shahadat Hossain said by phone.

Four advisers to the caretaker government, meanwhile, held meetings Monday and Tuesday with representatives of all major parties to find a solution to end the latest political standoff. They were set to meet more politicians Wednesday.

Two people have been killed and dozens injured in the violence since the weekend protests.

Bangladesh has a history of political violence. The impoverished South Asian nation has witnessed two presidents slain in military coups and 19 other failed coup attempts since it gained independence from Pakistan in 1971.