CAIRO - Average yields on Egypt's six-month and one-year treasury bills were mixed at an auction on Thursday, data from the central bank showed.

The average yield on the 182-day bill slipped to 18.402 percent from 18.434 percent at the last similar auction, and the yield on the 364-day bill rose slightly to 17.871 percent from 17.868 percent.

Foreign holdings in Egyptian treasurliies totalled 306.5 billion Egyptian pounds ($17.4 billion) as of Sept 26, up from 300 billion Egyptian pounds a week earer, said Sami Khallaf, the head of public debt at the Finance Ministry.

Demand for Egypt's domestic debt has grown since the central bank raised base interest rates by 2 percentage points in July, the third increase since the country floated its currency last November. ($1 = 17.6000 Egyptian pounds)

(Reporting by Nadine Awadalla; editing by John Stonestreet) ((Nadine.Awadalla@thomsonreuters.com;))