DUBAI, Aug 30 (Reuters) - The Qatar central bank has invited banks to bid in a 1 billion riyal ($275 million) Treasury bill auction to be held on Wednesday, according to a document seen by Reuters.

The bills would be sold in three-, six- and nine-month tranches, with results of the monthly sale to be revealed on Thursday, the document showed.

Between January and March, the central bank cancelled monthly sales of T-bills because of tightening liquidity in the banking system due to low oil and gas prices. But since then, liquidity has improved somewhat, and the sales have resumed. In the last sale on Aug. 2, it issued 1.2 billion riyals of bills.

(Reporting by Hadeel Al Sayegh; Editing by Andrew Torchia) ((Hadeel.AlSayegh@thomsonreuters.com; +971566883310;))