DUBAI, Aug 15 (Reuters) - Qatar's central bank is offering 3 billion riyals ($825 million) of government bonds, its first domestic bond sale this year, pointing to improved liquidity in a banking system strained by low oil and gas prices.

The offer comprises 1.5 billion riyals of three-year bonds, 1 billion riyals of five-year debt, 250 million riyals of seven-year debt and 250 million riyals of 10-year debt, according to an offer document seen by Reuters.

(Editing by Andrew Torchia and John Stonestreet) ((Tom.Finn@thomsonreuters.com;))