UPDATE 2-Bain in $1.1 bln deal for Citi's Bellsystem-sources

* Largest foreign private equity deal in Japan in almost 2 yrs

* Bain beats Permira, CVC Capital and Blackstone -sources

* Official announcement could be made in next few days-sources (Adds background)

By Junko Fujita and Megan Davies

TOKYO/NEW YORK, Nov 13 (Reuters) - U.S. private equity firm Bain Capital is finalising a roughly 100 billion yen ($1.1 billion) deal to buy Japanese telemarketer Bellsystem24 from Citigroup Inc (C.N), three sources familiar with the the matter said.

It would be the largest buyout by a foreign private equity firm in Japan in nearly two years.

Bain has beaten off rivals Permira [PERM.UL] and a team of CVC Capital and Blackstone (BX.N), which had also made offers in the final round of bidding for Bellsystem24, the sources said, speaking on condition of anonymity because the talks are not public.

Bain is working on final details and an official announcement could be made within the next few days, the sources told Reuters.

"A deal is imminent," one of the sources said.