Image caption Police say thousands of workers clashed with security forces at Ashulia

Owners have shut all 250 garment factories at one of Bangladesh's main manufacturing zones after violent protests by workers over wages.

Employers say production at Ashulia near Dhaka has stopped indefinitely.

Thousands of workers reacted angrily to the news, burning tyres and smashing vehicles in a third day of protests.

Bangladesh relies heavily on textile exports. Among factories shut were ones supplying Walmart, H&M, Zara, and Carrefour, manufacturers said.

Pay and working conditions in factories in Bangladesh have long been a source of concern.

The BBC's Mark Dummett in Dhaka says the industrial unrest is the worst Bangladesh has seen in several years.

'Anarchy'

Workers want three times the current minimum wage of $25 (£17) a month. The rate, set by the Bangladesh government, was last raised in 2006.

The latest unrest over pay began on Saturday, since when there has been a wave of violent demonstrations.

Manufacturers say they cannot keep their factories open because of the violence.

On Monday, tens of thousands of workers walked out of factories and held protests in Ashulia, about 30km (20 miles) north of Dhaka.

Police fired rubber bullets and tear gas. Workers pelted them with stones and set vehicles alight.

Thousands of protesters returned to the streets again on Tuesday when they heard about the factory closures.

"Striking workers picketed on the street, by burning tyres and smashing vehicles and set fire to a truck," Dhaka district police chief Iqbal Bahar told the BBC.

He said the situation had later been brought under control. At least 30 people were reported to have been injured in the latest unrest.

Siddiqur Rahman, vice-president of the Bangladesh Garment Manufacturers and Exporters' Association (BGMEA), told the BBC there was now "a state of anarchy" in Ashulia's garment factories.

"In the past few weeks, angry workers vandalised around 200 garment factories," he said.

"We feel insecure and unable to run the factories for the collapse of the law and order situation. So we closed down all 250 factories in Ashulia."

Mr Rahman said that garment factories inside another key manufacturing area - the Export Processing Zone - were still working.

Poorly paid

Garments are easily Bangladesh's biggest export, accounting for more than 80% of annual export earnings worth $15bn.

Our correspondent says food and property prices have risen sharply since the minimum wage was last raised in 2006. The current salary means Bangladeshi garment workers are among the lowest paid in the world.

This has led to a boom in recent years as factory owners have won hundreds of new contracts.

Factory owners say growth will be damaged if they increase salaries, but workers say they are not being paid a living wage.