"It's about 4 billion, divided between both Islamic and regular (debt). The maturities will be ... three months, six months and nine months," the source said.

The issuance will be the fourth this year by Qatar's central bank.

"The primary motivator for this is to help manage liquidity and create a yield curve for the market," said John Sfakianakis, chief economist at Banque Saudi Fransi in Riyadh.

In April, Qatar's central bank slashed key interest rates by at least 50 basis points for the first time since August, in a move that analysts said was aimed at boosting domestic lending and reducing capital inflows.

Qatar's copious natural gas reserves have turned it into an economic powerhouse, with economic growth expected to reach 16.7 percent this year.

Copyright Reuters, 2011