TOKYO, Dec 25 (Reuters) - Sumitomo Mitsui Banking Corp has agreed to buy Citigroup Inc's Japanese retail banking business and merge it with its subsidiary SMBC Trust Bank, the companies said on Thursday.

The acquisition price was not disclosed. Sources with knowledge of the deal had told Reuters that SMBC, a unit of Sumitomo Mitsui Financial Group Inc, would acquire the business for about 40 billion yen ($333 million).

Citi said the deal was expected to close in late 2015 subject to regulatory approvals.

Citigroup said in October it was pulling out of consumer banking in 11 markets, including Japan, to cut costs. Its Japanese consumer banking business has been hurt by weak loan demand and falling interest margins.

($1 = 120.3700 yen) (Reporting by Chris Gallagher; Editing by Edmund Klamann)