SINGAPORE/JAKARTA, April 17 (Reuters) - Abu Dhabi's largest Islamic bank is in talks to buy a minority stake valued at around $1.1 billion in Indonesia's top Islamic lender, Bank Syariah Indonesia, sources said, with an aim to tap into a fast-growing market for such services in Southeast Asia.

The potential acquisition of a 15% stake in Bank Syariah Indonesia (BSI) from Bank Rakyat Indonesia (BRI) is one of the options that Abu Dhabi Islamic Bank (ADIB) is considering, said the two sources familiar with the matter.

The sources declined to be named as they were not authorised to speak to the media.

ADIB declined to comment.

"What we can say is that the information above is in the domain of our shareholders," state-owned BSI's corporate secretary Gunawan Hartoyo said in a statement in response to Reuters' queries. (Reporting by Yantoultra Ngui in Singapore and Stefanno Sulaiman in Jakarta; Editing by Sumeet Chatterjee and Mark Potter)