World stock markets have been falling again after weak figures from the troubled US housing market reignited concerns over the outlook for the world's largest economy.

Shares of financial institutions were among the worst hit, despite Britain's Barclays' denying a newspaper report that failed debt vehicles structured by its investment banking arm had left it with an exposure worth hundreds of millions of dollars.

Stocks in Dublin are down more 2.5% this evening with Irish banks showing the biggest declines after a gloomy report on the financial sector from Davy Stockbrokers.

Anglo Irish Bank, Bank of Ireland and AIB are down about 3%.

In London shares are down almost 2% and in New York shares have slipped over 1%.

The recent atmosphere of calm in the markets ended this afternoon with a fresh wave of investors selling shares.

Most of the problems are due to more bad news from the States.

Property values in the US are falling by 1% a month and it is also becoming harder for consumers to get loans which is hitting the profits of banks.

Data released on Monday showed that the number of unsold homes in the US reached its highest level in more than 15 years in July, fuelling worries over the housing market and the impact on consumer spending.

Stock markets worldwide have recently been hit by fears that a rising number of defaults in the US sub-prime mortgage market could translate into big losses for financial institutions and dampen economic growth.