Media playback is unsupported on your device Media caption Police stand guard around the Dhaka Stock Exchange

Bangladeshi police have used tear gas and water cannon against angry investors after the stock market incurred huge losses.

Trading on the Dhaka Stock Exchange index was halted after it fell by 660 points, or 9.25%, in less than an hour.

It was the biggest one-day fall in its 55-year history.

It is estimated that over three million people - many of them small-scale individual investors - have lost money because of the plunging share prices.

The benchmark index had climbed by 80% in 2010 but has lost more than 27% since early December.

Investors and police also clashed last month.

Monday's protest followed losses of about 6.7% in Sunday trading.

Trading was also halted on the country's other main index, the Chittagong Stock Exchange.

Rumours and panic

Police say that they are now firmly in control of Dhaka's business district and have closed roads leading to the stock exchange.

Earlier, officers baton-charged about 5,000 investors to clear them from the area.

Image caption Investors were not pleased to find that shares can go down as well as up

They had gathered to protest against the closing of the exchange after the record fall. Vehicles were vandalised and bonfires were lit at traffic intersections.

"They started vandalising government property, which forced us to use batons against them," police inspector Azizul Haq told the AFP news agency.

One of the protesters, Mukul Ahmed, said he had lost $3,000 (£1,932) in the market over the last three weeks.

There was also violence in the port city of Chittagong - which has its own exchange.

The government regulator, the Securities and Exchange Commission, held an emergency meeting on Monday with merchant bankers and institutional stockbrokers to discuss saving the market from further falls.

The rising value of the stocks in recent years has attracted millions of investors in Bangladesh.

Shares have become a popular investment for ordinary people, often providing higher returns than bank deposits and savings.

The BBC's Mark Dummett says that Bangladesh might be one of Asia's poorest countries, but its two stock markets have soared in recent years on the rising value of its mobile telephone companies and other firms.

But over the past few weeks more and more investors have been selling up, amid rumours that large institutional investors had pulled their money out after making large profits.

In recent weeks, regulators have taken measures to limit the proportion of deposits that banks can invest into the stock market - after concerns that shares were over-valued.

This move forced big institutional investors to withdraw from the market, triggering panic among individual investors.