DUBAI, Jan 15 (Reuters) - Morocco's central bank sold $3.5 million in its first auction of U.S. dollars under a more flexible foreign exchange system which it introduced on Monday, the bank said.

It sold the dollars at a weighted average rate of 9.2307 dirhams, with a marginal rate of 9.2304 dirhams. The central bank had offered $20 million; demand in the auction totalled $3.5 million, with bids falling between 9.2304 and 9.2310.

(Reporting by Aziz El Yaakoubi, Writing by Andrew Torchia) ((andrew.torchia@thomsonreuters.com; +9715 6681 7277; Reuters Messaging: andrew.torchia.thomsonreuters.com@reuters.net))