RIYADH - Saudi Arabia launched commercial courts in three main cities last month, its justice minister said, a move aimed at easing investment to help wean the kingdom off its reliance on oil by diversifying the economy.

Changes being made to the Saudi legal system are a key aspect of wider social and economic reforms meant to reconcile the country's ultra-conservative Islamic traditions with the demands of a young population and modern economy, analysts say.

Justice Minister Walid Al-Samaani said the specialised courts in Riyadh, Dammam and Jeddah, as well as appeal centres in other cities, would help promote a business climate built on trust and expedite the resolution of commercial disputes.

"The start of operations of these courts is a quantum leap and a major development for the specialised courts," Samaani was quoted as saying by state news agency SPA on Sunday.

"This would be very welcomed by the business community, judges would be trained for specialised disputes, investors will also be more and more confident agreements will be enforceable by a commercial court," said a Saudi lawyer, who asked not to be named.

It was not immediately known if the new courts had begun handling cases.

The decision fit in with a trend toward more specialised applications of the law in Saudi Arabia, a departure from decades of tradition in which judges have used their interpretation of Islamic texts to rule on cases that range from complex commercial disputes to murder.

The Saudi system of sharia, or Islamic law, is not codified and has no system of precedent. Judges have extensive powers to pass verdicts and impose sentences according to their personal readings of Muslim texts.

While most commercial cases are now handled through arbitration and business tribunals, foreign investors and local businesses have said in the past that they want a stronger legal framework for settling disputes.

Currently, business and general disputes are filed to a Board of Grievances. There are disputes committees for the banking and insurance sectors and for the stock market regulator, the Saudi Capital Market Authority (CMA).

(Reporting by Reem Shamseddine; editing by Mark Heinrich) ((Reem.Shamseddine@thomsonreuters.com; +966503335202; Reuters Messaging: reem.shamseddine.thomsonreuters.com@reuters.net))