CAIRO, June 17 (Reuters) - The average yield on three- and seven-year Egyptian treasury bonds rose at an auction on Monday, and the central bank sold far less debt than it had intended to.

Bankers say some investors are cautious ahead of countrywide anti-government protests planned for June 30 amid fears they may turn violent.

The average yield for three-year bonds rose to 15.440 percent from 15.335 percent at the last auction on June 3, the central bank said. Yields on the seven-year bond rose to 16.133 percent from 15.805 percent at the previous auction on June 3.

The bonds were reopened, with the three-year maturing on May 7, 2016, and the seven-year maturing on May 21, 2020.

The central bank had offered 1 billion Egyptian pounds ($143 million) in each maturity, but sold only 668.8 million pounds' worth of the three-year bonds and 700 million pounds' worth of the seven-year paper.

($1 = 6.9933 Egyptian pounds)

(Reporting by Asma Alsharif; Editing by Hugh Lawson)

((asma.alsharif@thomsonreuters.com)(+20225783290)(Reuters Messaging: asma.alsharif.reuters.com@reuters.net))

Keywords: EGYPT AUCTION/