By Robert Hogg

LONDON, May 23 (IFR) - The Sultanate of Oman has started marketing a seven-year US dollar benchmark-sized sukuk offering at 270bp area over mid-swaps, according to a lead.

Books are open for pricing as early as today's business via Alizz Islamic Bank, Citigroup, Dubai Islamic Bank, Gulf International Bank, HSBC, JP Morgan and Standard Chartered (B&D).

The sovereign had signalled the possibility of an additional 12-year sukuk in its mandate but no further details have been provided on that tranche.

Expected issue ratings are Baa1 by Moody's and BBB by Fitch.

(Reporting by Robert Hogg; editing by Sudip Roy) ((Robert.Hogg@thomsonreuters.com; +44 207 542 9077;))