DOHA, Jan 17 (Reuters) - Qatar's central bank sold 15 billion riyals ($4.1 billion) of conventional and Islamic government bonds on Sunday in its first domestic government debt offer this year, a Qatar central bank official told Reuters on Tuesday.

"We issued 7 billion in bonds in an auction that was oversubscribed by 100 million riyals - 8 billion in sukuk was issued as well," said the official, who declined to be named.

The official did not give further details.

A document seen by Reuters showed the central bank offered three-year bonds at 2.50 percent, five-year bonds at 3.10 percent, seven-year bonds at 3.75 percent, and 10-year bonds at 4.25 percent.

The document did not specify how many bonds would be sold, but commercial bankers said they believed the issue would offset the maturing of about 15 billion riyals of government bonds this month.

(Reporting by Tom Finn; Editing by Andrew Torchia) ((;))