Qatar Exchange, the country's securities market, cancelled all transactions executed on Tuesday after an unspecified technical problem disrupted its trading platform.

The highly unusual decision is a blow to Qatar just as the exchange, one of the Gulf's top stock markets whose listed companies have a combined market value of about $130 billion, is reforming its trading practices in an effort to attract more foreign money.

"After consultation with QFMA (Qatar Financial Markets Authority), it was agreed to cancel all transactions that took place today and any orders that had not been executed," the exchange said in an emailed statement.

"This was decided because the incident had affected the flow of information and the brokers' ability to execute their clients' orders in a sound and correct manner."

The exchange said it hoped to resume trading as usual on Wednesday morning. It gave no details of the technical problem, which had initially brought trading to a halt during the morning, before it resumed for a short time, then halted again for the rest of the day.

Senior exchange officials could not be contacted to comment further on the incident.

Investors had traded 7.37 million shares in the Qatar market's 20-stock main index when trading halted, according to exchange data. On Monday, a normal trading day, the entire market traded a total of 19.7 million shares worth a total of 641 million riyals ($176 million).

The index on Monday set its highest closing level for five years, up 24 percent year-to-date.

The exchange's chief executive Rashid Bin Ali Al-Mansoori told Reuters last month that among other steps, Qatar Exchange had submitted proposals to the government for higher limits on foreign ownership of stocks, which could encourage more firms to make initial public offers of their shares.

The market received a boost in June when international equity index compiler MSCI decided to upgrade Qatar and the United Arab Emirates to "emerging market" from "frontier market" status. Inflows of foreign funds are expected to increase next May when the upgrade takes effect.

As part of a drive to internationalise Qatar's market, NYSE Euronext bought a 20 percent stake in Qatar Exchange for $200 million in 2009. Last month Qatar Holding, the investment arm of the country's sovereign wealth fund, bought out NYSE Euronext and ownership of the exchange is now entirely local. - Reuters